Release 2 docs (#3976)

* Add v1.0 blog post and update reference paper. (#3947)

* Develop mm fix readme releases (#3966)

* Fix broken link and clean-up Releases section.

* Updated link to be consistent with the table.

* Update one of the bullets for consistency.

* update table, add Versioning doc

* release_2_docs

Co-authored-by: Marwan Mattar <marwan@unity3d.com>

README.md

 
 # Unity ML-Agents Toolkit
 
-[![docs badge](https://img.shields.io/badge/docs-reference-blue.svg)](https://github.com/Unity-Technologies/ml-agents/tree/release_1_docs/docs/)
+[![docs badge](https://img.shields.io/badge/docs-reference-blue.svg)](https://github.com/Unity-Technologies/ml-agents/tree/release_2_docs/docs/)
 
 [![license badge](https://img.shields.io/badge/license-Apache--2.0-green.svg)](LICENSE)
 
 
 ## Releases & Documentation
 
-**Our latest, stable release is `Release 1`. Click [here](docs/Readme.md) to
-get started with the latest release of ML-Agents.**
+**Our latest, stable release is `Release 2`. Click
+[here](https://github.com/Unity-Technologies/ml-agents/tree/release_2_docs/docs/Readme.md)
+to get started with the latest release of ML-Agents.**
-The table below lists all our releases, including our `master` branch which is under active
-development and may be unstable. A few helpful guidelines:
-* The docs links in the table below include installation and usage instructions specific to each
-release. Remember to always use the documentation that corresponds to the release version you're
-using.
-* See the [GitHub releases](https://github.com/Unity-Technologies/ml-agents/releases) for more
-details of the changes between versions.
-* If you have used an earlier version of the ML-Agents Toolkit, we strongly recommend our
-[guide on migrating from earlier versions](docs/Migrating.md).
+The table below lists all our releases, including our `master` branch which is
+under active development and may be unstable. A few helpful guidelines:
+- The [Versioning page](docs/Versioning.md) overviews how we manage our GitHub
+  releases and the versioning process for each of the ML-Agents components.
+- The [Releases page](https://github.com/Unity-Technologies/ml-agents/releases)
+  contains details of the changes between releases.
+- The [Migration page](docs/Migrating.md) contains details on how to upgrade
+  from earlier releases of the ML-Agents Toolkit.
+- The **Documentation** links in the table below include installation and usage
+  instructions specific to each release. Remember to always use the
+  documentation that corresponds to the release version you're using.
-| **Release 1** | **April 30, 2020** | **[source](https://github.com/Unity-Technologies/ml-agents/tree/release_1)** | **[docs](https://github.com/Unity-Technologies/ml-agents/tree/release_1/docs/Readme.md)** | **[download](https://github.com/Unity-Technologies/ml-agents/archive/release_1.zip)** |
+| **Release 2** | **May 19, 2020** | **[source](https://github.com/Unity-Technologies/ml-agents/tree/release_2)** | **[docs](https://github.com/Unity-Technologies/ml-agents/tree/release_2/docs/Readme.md)** | **[download](https://github.com/Unity-Technologies/ml-agents/archive/release_2.zip)** |
+| **Release 1** | April 30, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/release_1) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/release_1/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/release_1.zip) |
 | **0.15.1** | March 30, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.15.1) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.15.1/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.15.1.zip) |
 | **0.15.0** | March 18, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.15.0) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.15.0/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.15.0.zip) |
 | **0.14.1** | February 26, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.14.1) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.14.1/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.14.1.zip) |
-| **0.12.1** | December 11, 2019 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.12.1) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.12.1/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.12.1.zip) |
-| **0.12.0** | December 2, 2019 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.12.0) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.12.0/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.12.0.zip) |
-
 ## Citation
 
 If you are a researcher interested in a discussion of Unity as an AI platform,
 If you use Unity or the ML-Agents Toolkit to conduct research, we ask that you
 cite the following paper as a reference:
 
-Juliani, A., Berges, V., Vckay, E., Gao, Y., Henry, H., Mattar, M., Lange, D.
-(2018). Unity: A General Platform for Intelligent Agents. _arXiv preprint
-arXiv:1809.02627._ https://github.com/Unity-Technologies/ml-agents.
+Juliani, A., Berges, V., Teng, E., Cohen, A., Harper, J., Elion, C., Goy, C.,
+Gao, Y., Henry, H., Mattar, M., Lange, D. (2020). Unity: A General Platform for
+Intelligent Agents. _arXiv preprint
+[arXiv:1809.02627](https://arxiv.org/abs/1809.02627)._
+https://github.com/Unity-Technologies/ml-agents.
+- (May 12, 2020)
+  [Announcing ML-Agents Unity Package v1.0!](https://blogs.unity3d.com/2020/05/12/announcing-ml-agents-unity-package-v1-0/)
 - (February 28, 2020)
   [Training intelligent adversaries using self-play with ML-Agents](https://blogs.unity3d.com/2020/02/28/training-intelligent-adversaries-using-self-play-with-ml-agents/)
 - (November 11, 2019)

com.unity.ml-agents/Runtime/Academy.cs

  * API. For more information on each of these entities, in addition to how to
  * set-up a learning environment and train the behavior of characters in a
  * Unity scene, please browse our documentation pages on GitHub:
- * https://github.com/Unity-Technologies/ml-agents/tree/release_1_docs/docs/
+ * https://github.com/Unity-Technologies/ml-agents/tree/release_2_docs/docs/
  */
 
 namespace Unity.MLAgents
     /// fall back to inference or heuristic decisions. (You can also set agents to always use
     /// inference or heuristics.)
     /// </remarks>
-    [HelpURL("https://github.com/Unity-Technologies/ml-agents/tree/release_1_docs/" +
+    [HelpURL("https://github.com/Unity-Technologies/ml-agents/tree/release_2_docs/" +
         "docs/Learning-Environment-Design.md")]
     public class Academy : IDisposable
     {

com.unity.ml-agents/Runtime/Agent.cs

     /// [OnDisable()]: https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnDisable.html]
     /// [OnBeforeSerialize()]: https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnBeforeSerialize.html
     /// [OnAfterSerialize()]: https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnAfterSerialize.html
-    /// [Agents]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md
-    /// [Reinforcement Learning in Unity]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design.md
+    /// [Agents]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md
+    /// [Reinforcement Learning in Unity]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design.md
-    /// [Unity ML-Agents Toolkit manual]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Readme.md
+    /// [Unity ML-Agents Toolkit manual]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Readme.md
-    [HelpURL("https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/" +
+    [HelpURL("https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/" +
         "docs/Learning-Environment-Design-Agents.md")]
     [Serializable]
     [RequireComponent(typeof(BehaviorParameters))]
         /// for information about mixing reward signals from curiosity and Generative Adversarial
         /// Imitation Learning (GAIL) with rewards supplied through this method.
         ///
-        /// [Agents - Rewards]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#rewards
-        /// [Reward Signals]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/ML-Agents-Overview.md#a-quick-note-on-reward-signals
+        /// [Agents - Rewards]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#rewards
+        /// [Reward Signals]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/ML-Agents-Overview.md#a-quick-note-on-reward-signals
         /// </remarks>
         /// <param name="reward">The new value of the reward.</param>
         public void SetReward(float reward)
         /// for information about mixing reward signals from curiosity and Generative Adversarial
         /// Imitation Learning (GAIL) with rewards supplied through this method.
         ///
-        /// [Agents - Rewards]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#rewards
-        /// [Reward Signals]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/ML-Agents-Overview.md#a-quick-note-on-reward-signals
+        /// [Agents - Rewards]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#rewards
+        /// [Reward Signals]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/ML-Agents-Overview.md#a-quick-note-on-reward-signals
         ///</remarks>
         /// <param name="increment">Incremental reward value.</param>
         public void AddReward(float increment)
         /// implementing a simple heuristic function can aid in debugging agent actions and interactions
         /// with its environment.
         ///
-        /// [Demonstration Recorder]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#recording-demonstrations
-        /// [Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#actions
+        /// [Demonstration Recorder]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#recording-demonstrations
+        /// [Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#actions
         /// [GameObject]: https://docs.unity3d.com/Manual/GameObjects.html
         /// </remarks>
         /// <example>
         /// For more information about observations, see [Observations and Sensors].
         ///
         /// [GameObject]: https://docs.unity3d.com/Manual/GameObjects.html
-        /// [Observations and Sensors]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#observations-and-sensors
+        /// [Observations and Sensors]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#observations-and-sensors
         /// </remarks>
         public virtual void CollectObservations(VectorSensor sensor)
         {
         ///
         /// See [Agents - Actions] for more information on masking actions.
         ///
-        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#actions
+        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#actions
         /// </remarks>
         /// <seealso cref="OnActionReceived(float[])"/>
         public virtual void CollectDiscreteActionMasks(DiscreteActionMasker actionMasker)
         ///
         /// For more information about implementing agent actions see [Agents - Actions].
         ///
-        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#actions
+        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#actions
         /// </remarks>
         /// <param name="vectorAction">
         /// An array containing the action vector. The length of the array is specified

com.unity.ml-agents/Runtime/Demonstrations/DemonstrationRecorder.cs

     /// See [Imitation Learning - Recording Demonstrations] for more information.
     ///
     /// [GameObject]: https://docs.unity3d.com/Manual/GameObjects.html
-    /// [Imitation Learning - Recording Demonstrations]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs//Learning-Environment-Design-Agents.md#recording-demonstrations
+    /// [Imitation Learning - Recording Demonstrations]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs//Learning-Environment-Design-Agents.md#recording-demonstrations
     /// </remarks>
     [RequireComponent(typeof(Agent))]
     [AddComponentMenu("ML Agents/Demonstration Recorder", (int)MenuGroup.Default)]

com.unity.ml-agents/Runtime/DiscreteActionMasker.cs

         ///
         /// See [Agents - Actions] for more information on masking actions.
         ///
-        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_1_docs/docs/Learning-Environment-Design-Agents.md#actions
+        /// [Agents - Actions]: https://github.com/Unity-Technologies/ml-agents/blob/release_2_docs/docs/Learning-Environment-Design-Agents.md#actions
         /// </remarks>
         /// <param name="branch">The branch for which the actions will be masked.</param>
         /// <param name="actionIndices">The indices of the masked actions.</param>

utils/make_readme_table.py

     ReleaseInfo.from_simple_tag("0.15.0", "March 18, 2020"),
     ReleaseInfo.from_simple_tag("0.15.1", "March 30, 2020"),
     ReleaseInfo("release_1", "1.0.0", "0.16.0", "April 30, 2020"),
+    ReleaseInfo("release_2", "1.0.1", "0.16.1", "May 19, 2020"),
 ]
 
 MAX_DAYS = 150  # do not print releases older than this many days

docs/Versioning.md

+# ML-Agents Versioning
+
+## Context
+As the ML-Agents project evolves into a more mature product, we want to communicate the process
+we use to version our packages and the data that flows into, through, and out of them clearly.
+Our project now has four packages (1 Unity, 3 Python) along with artifacts that are produced as
+well as consumed.  This document covers the versioning for these packages and artifacts.
+
+## GitHub Releases
+Up until now, all packages were in lockstep in-terms of versioning. As a result, the GitHub releases
+were tagged with the version of all those packages (e.g. v0.15.0, v0.15.1) and labeled accordingly.
+With the decoupling of package versions, we now need to revisit our GitHub release tagging.
+The proposal is that we move towards an integer release numbering for our repo and each such
+release will call out specific version upgrades of each package. For instance, with
+[the April 30th release](https://github.com/Unity-Technologies/ml-agents/releases/tag/release_1),
+we will have:
+- GitHub Release 1 (branch name: *release_1_branch*)
+  - com.unity.ml-agents release 1.0.0
+  - ml-agents release 0.16.0
+  - ml-agents-envs release 0.16.0
+  - gym-unity release 0.16.0
+
+Our release cadence will not be affected by these versioning changes.  We will keep having
+monthly releases to fix bugs and release new features.
+
+## Packages
+All of the software packages, and their generated artifacts will be versioned.  Any automation
+tools will not be versioned.
+
+### Unity package
+Package name: com.unity.ml-agents
+- Versioned following [Semantic Versioning Guidelines](https://www.semver.org)
+- This package consumes an artifact of the training process: the `.nn` file.  These files
+    are integer versioned and currently at version 2. The com.unity.ml-agents package
+    will need to support the version of `.nn` files which existed at its 1.0.0 release.
+    For example, consider that com.unity.ml-agents is at version 1.0.0 and the NN files
+    are at version 2.  If the NN files change to version 3, the next release of
+    com.unity.ml-agents at version 1.1.0 guarantees it will be able to read both of these
+    formats.  If the NN files were to change to version 4 and com.unity.ml-agents to
+    version 2.0.0, support for NN versions 2 and 3 could be dropped for com.unity.ml-agents
+    version 2.0.0.
+- This package produces one artifact, the `.demo` files.  These files will have integer
+    versioning. This means their version will increment by 1 at each change.  The
+    com.unity.ml-agents package must be backward compatible with version changes
+    that occur between minor versions.
+- To summarize, the artifacts produced and consumed by com.unity.ml-agents are guaranteed
+    to be supported for 1.x.x versions of com.unity.ml-agents.  We intend to provide stability
+    for our users by moving to a 1.0.0 release of com.unity.ml-agents.
+
+
+### Python Packages
+Package names: ml-agents / ml-agents-envs / gym-unity
+- The python packages remain in "Beta."  This means that breaking changes to the public
+    API of the python packages can change without having to have a major version bump.
+    Historically, the python and C# packages were in version lockstep.  This is no longer
+    the case.  The python packages will remain in lockstep with each other for now, while the
+    C# package will follow its own versioning as is appropriate.  However, the python package
+    versions may diverge in the future.
+- While the python packages will remain in Beta for now, we acknowledge that the most
+    heavily used portion of our python interface is the `mlagents-learn` CLI and strive
+    to make this part of our API backward compatible. We are actively working on this and
+    expect to have a stable CLI in the next few weeks.
+
+## Communicator
+
+Packages which communicate: com.unity.ml-agents / ml-agents-envs
+
+Another entity of the ML-Agents Toolkit that requires versioning is the communication layer
+between C# and Python, which will follow also semantic versioning.  This guarantees a level of
+backward compatibility between different versions of C# and Python packages which communicate.
+Any Communicator version 1.x.x of the Unity package should be compatible with any 1.x.x
+Communicator Version in Python.
+
+An RLCapabilities struct keeps track of which features exist. This struct is passed from C# to
+Python, and another from Python to C#.  With this feature level granularity, we can notify users
+more specifically about feature limitations based on what's available in both C# and Python.
+These notifications will be logged to the python terminal, or to the Unity Editor Console.
+
+
+## Side Channels
+
+The communicator is what manages data transfer between Unity and Python for the core
+training loop. Side Channels are another means of data transfer between Unity and Python.
+Side Channels are not versioned, but have been designed to support backward compatibility
+for what they are. As of today, we provide 4 side channels:
+- FloatProperties: shared float data between Unity - Python (bidirectional)
+- RawBytes: raw data that can be sent Unity - Python (bidirectional)
+- EngineConfig: a set of numeric fields in a pre-defined order sent from Python to Unity
+- Stats: (name, value, agg) messages sent from Unity to Python
+
+Aside from the specific implementations of side channels we provide (and use ourselves),
+the Side Channel interface is made available for users to create their own custom side
+channels. As such, we guarantee that the built in SideChannel interface between Unity and
+Python is backward compatible in packages that share the same major version.
+