Develop mm doc improvements (#3741)

* Fix the main releases table by generating from the script.

* Minor formatting fix

* Removing references to Cloud Training as those docs are now deprecated.

* Removing the link to video tutorials as they are now not current

README.md

 |:-------:|:------:|:-------------:|:-------:|:------------:|
 | **master (unstable)** | -- | [source](https://github.com/Unity-Technologies/ml-agents/tree/master) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/master/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/master.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)** |
+| **0.15.0** | 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) |
 | **0.14.0** | February 13, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.14.0) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.14.0/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.14.0.zip) |
 | **0.13.1** | January 21, 2020 | [source](https://github.com/Unity-Technologies/ml-agents/tree/0.13.1) | [docs](https://github.com/Unity-Technologies/ml-agents/tree/0.13.1/docs/Readme.md) | [download](https://github.com/Unity-Technologies/ml-agents/archive/0.13.1.zip) |

docs/Getting-Started.md

 - For a "Hello World" introduction to creating your own Learning Environment,
   check out the [Making a New Learning
   Environment](Learning-Environment-Create-New.md) page.
-- For a series of YouTube video tutorials, checkout the
-  [Machine Learning Agents PlayList](https://www.youtube.com/playlist?list=PLX2vGYjWbI0R08eWQkO7nQkGiicHAX7IX)
-  page.

docs/ML-Agents-Overview.md

   [Training With Environment Parameter Randomization](Training-Environment-Parameter-Randomization.md)
   to learn more about this feature.
 
-- **Cloud Training on AWS** - To facilitate using the ML-Agents toolkit on
-  Amazon Web Services (AWS) machines, we provide a
-  [guide](Training-on-Amazon-Web-Service.md) on how to set-up EC2 instances in
-  addition to a public pre-configured Amazon Machine Image (AMI).
-
-- **Cloud Training on Microsoft Azure** - To facilitate using the ML-Agents
-  toolkit on Azure machines, we provide a
-  [guide](Training-on-Microsoft-Azure.md) on how to set-up virtual machine
-  instances in addition to a pre-configured data science image.
-
 ## Summary and Next Steps
 
 To briefly summarize: The ML-Agents toolkit enables games and simulations built

docs/Training-ML-Agents.md

 * `--debug`: Specify this option to enable debug-level logging for some parts of the code.
 * `--cpu`: Forces training using CPU only.
 * Engine Configuration :
-  * `--width' : The width of the executable window of the environment(s) in pixels
+  * `--width` : The width of the executable window of the environment(s) in pixels
   (ignored for editor training) (Default 84)
   * `--height` : The height of the executable window of the environment(s) in pixels
   (ignored for editor training). (Default 84)

utils/make_readme_table.py

     ["0.14.0", "February 13, 2020"],
     ["0.14.1", "February 26, 2020"],
     ["0.15.0", "March 18, 2020"],
+    ["0.15.1", "March 30, 2020"],
 ]
 
 MAX_DAYS = 150  # do not print releases older than this many days