Update code review comments

Author: goanpeca

ignite/engine/engine.py

@@ -328,7 +328,6 @@ def execute_something():
 
         try:
             _check_signature(handler, "handler", self, *(event_args + args), **kwargs)
-            # Use weak reference to break circular reference
             self._event_handlers[event_name].append((handler, (weakref.ref(self),) + args, kwargs))
         except ValueError:
             _check_signature(handler, "handler", *(event_args + args), **kwargs)