Add method documentations (#4553)

Author: Ruo-Ping (Rachel) Dong

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

@@ -64,6 +64,16 @@ public static bool CompareObservation(ISensor sensor, float[] expected, out stri
             return true;
         }
 
+        /// <summary>
+        /// Generates the observations for the provided sensor, and returns true if they equal the
+        /// expected values. If they are unequal, errorMessage is also set.
+        /// This should not generally be used in production code. It is only intended for
+        /// simplifying unit tests.
+        /// </summary>
+        /// <param name="sensor"></param>
+        /// <param name="expected"></param>
+        /// <param name="errorMessage"></param>
+        /// <returns></returns>
         public static bool CompareObservation(ISensor sensor, float[,,] expected, out string errorMessage)
         {
             var tensorShape = new TensorShape(0, expected.GetLength(0), expected.GetLength(1), expected.GetLength(2));

com.unity.ml-agents/Runtime/Sensors/StackingSensor.cs

@@ -202,6 +202,7 @@ public byte[] GetCompressedObservation()
             return outputBytes;
         }
 
+        /// <inheritdoc/>
         public int[] GetCompressedChannelMapping()
         {
             return m_CompressionMapping;
@@ -224,7 +225,6 @@ internal byte[] CreateEmptyPNG()
             return texture2D.EncodeToPNG();
         }
 
-
         /// <summary>
         /// Constrct stacked CompressedChannelMapping.
         /// </summary>