Changing the comments and docs relative to the change of the observation

Project/Assets/ML-Agents/Examples/Sorter/Scripts/SorterAgent.cs

         {
             // Each observation / tile in the BufferSensor will have 22 values
             // The first 20 are one hot encoding of the value of the tile
-            // The 21st is the angle of the tile on the circle wall
-            // The 22nd is a boolean : 1 if the tile was visited already and 0 otherwise
+            // The 21st and 22nd are the position of the tile relative to the agent
+            // The 23rd is a boolean : 1 if the tile was visited already and 0 otherwise
-            // listObservation[k_HighestTileValue] = (item.transform.localRotation.eulerAngles.y / 360f);
             listObservation[k_HighestTileValue + 2] = item.IsVisited ? 1.0f : 0.0f;
             // Here, the observation for the tile is added to the BufferSensor
             m_BufferSensor.AppendObservation(listObservation);

docs/Learning-Environment-Examples.md

   - Vector Observations : 4 : 2 floats for Position and 2 floats for orientation
   - Variable Length Observations : Between 1 and 20 entities (one for each tile)
   each with 22 observations, the first 20 are one hot encoding of the value of the tile,
-  the 21st represents the position of the tile and the 22nd is 1 if the tile was
-  visited and zero otherwise.
+  the 21st and 22nd represent the position of the tile relative to the Agent and the 23rd
+  is `1` if the tile was visited and `0` otherwise.
   - Actions: 3 discrete branched actions corresponding to forward, backward,
   sideways movement, as well as rotation.
   - Float Properties: One