added existential penaalty to generic soccer agent

Project/Assets/ML-Agents/Examples/Soccer/Scripts/AgentSoccer.cs

     public override void OnActionReceived(float[] vectorAction)
     {
 
-        // Generic gets nothing
-        if (position == Position.Striker)
+        if (position == Position.Goalie)
-            // Existential penalty for Strikers.
-            AddReward(-1f / 3000f);
+            // Existential bonus for Goalies.
+            AddReward(1f / 3000f);
-        else if (position == Position.Goalie)
+        else
-            // Existential bonus for Goalies.
-            AddReward(1f / 3000f);
+            // Existential penalty for Strikers/Generic.
+            AddReward(-1f / 3000f);
         }
         MoveAgent(vectorAction);
     }