Added comment to document invalid/null GameObject usage

SHADE_Managed/src/Engine/GameObject.hxx

@@ -31,6 +31,7 @@ namespace SHADE
     /// <summary>
     /// Lightweight object for an Entity that allows for easy access to Component and 
     /// Script operations.
+    /// Can be set to a invalid/null GameObject by default construction.
     /// </summary>
     public value class GameObject : public System::IEquatable<GameObject>
     {