Update docs regarding the "range" field in AddOneHotObservation (#16)

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

@@ -206,7 +206,7 @@ namespace Unity.MLAgents.Sensors
         /// Adds a one-hot encoding observation.
         /// </summary>
         /// <param name="observation">The index of this observation.</param>
-        /// <param name="range">The max index for any observation.</param>
+        /// <param name="range">The upper limit on the value observation can take (exclusive).</param>
         public void AddOneHotObservation(int observation, int range)
         {
             for (var i = 0; i < range; i++)

docs/Learning-Environment-Design-Agents.md

@@ -284,7 +284,7 @@ to the previous one.
 
 ```csharp
 enum ItemType { Sword, Shield, Bow, LastItem }
-const int NUM_ITEM_TYPES = (int)ItemType.LastItem;
+const int NUM_ITEM_TYPES = (int)ItemType.LastItem + 1;
 
 public override void CollectObservations(VectorSensor sensor)
 {