changelog, migration, fix name in obs

com.unity.ml-agents/CHANGELOG.md

 ## [Unreleased]
 ### Major Changes
 #### com.unity.ml-agents (C#)
+- Several breaking interface changes were made. See the
+[Migration Guide](https://github.com/Unity-Technologies/ml-agents/blob/release_14_docs/docs/Migrating.md) for more
+details.
-`SetActionEnabled(int branch, int actionIndex, bool isEnabled)`. See the
+`SetActionEnabled(int branch, int actionIndex, bool isEnabled)`. (#5060)
-[Migration Guide](https://github.com/Unity-Technologies/ml-agents/blob/release_14_docs/docs/Migrating.md) for more
-details. (#5060)
+- `ISensor.GetObservationShape()` was removed, and `GetObservationSpec()` was added. (#5127)
+
 #### ml-agents / ml-agents-envs / gym-unity (Python)
 
 ### Minor Changes

com.unity.ml-agents/Runtime/Communicator/GrpcExtensions.cs

                 }
             }
 
-            // Implement IEnumerable or IList?
+            }
+
+            var sensorName = sensor.GetName();
+            if (!string.IsNullOrEmpty(sensorName))
+            {
+                observationProto.Name = sensorName;
             }
 
             observationProto.ObservationType = (ObservationTypeProto)obsSpec.ObservationType;

docs/Migrating.md

 - The `IActuator` interface now implements `IHeuristicProvider`.  Please add the corresponding `Heuristic(in ActionBuffers)`
 method to your custom Actuator classes.
 
+- The `ISensor.GetObservationShape()` method was removed, and `GetObservationSpec()` was added. You can use
+`ObservationSpec.Vector()` or `ObservationSpec.Visual()` to generate `ObservationSpec`s that are equivalent to
+the previous shape. For example, if your old ISensor looked like:
+
+```csharp
+public override int[] GetObservationShape()
+{
+    return new[] { m_Height, m_Width, m_NumChannels };
+}
+```
+
+the equivalent code would now be
+
+```csharp
+public override ObservationSpec GetObservationSpec()
+{
+    return ObservationSpec.Visual(m_Height, m_Width, m_NumChannels);
+}
+```
+
 ## Migrating to Release 13
 ### Implementing IHeuristic in your IActuator implementations
  - If you have any custom actuators, you can now implement the `IHeuristicProvider` interface to have your actuator