Add comment regarding createentitiy

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitWorld.java

@@ -123,6 +123,8 @@ public class BukkitWorld extends AbstractWorld {
         return list;
     }
 
+    //createEntity was moved to IChunkExtent to prevent issues with Async Entitiy Add.
+    
     /**
      * Get the world handle.
      *