Docs: Improved Object3D.copy note.

docs/api/en/core/Object3D.html

@@ -230,7 +230,7 @@
 
 		Copy the given object into this object.
 
-		Note, the callbacks [page:.onAfterRender] and [page:.onBeforeRender] are not copied across.
+		Note: event listeners and user-defined callbacks ([page:.onAfterRender] and [page:.onBeforeRender]) are not copied.
 		</p>
 
 		<h3>[method:Object3D getObjectById]( [param:Integer id] )</h3>