Update description (#1337)

* Update base.py

* Update opendevin/action/base.py

---------

Co-authored-by: Robert Brennan <accounts@rbren.io>

opendevin/action/base.py

@@ -51,7 +51,6 @@ class NotExecutableAction(Action):
 @dataclass
 class NullAction(NotExecutableAction):
     """An action that does nothing.
-    This is used when the agent need to receive user follow-up messages from the frontend.
     """
 
     action: str = ActionType.NULL