Update comment.

Author: clokep

synapse/handlers/room_member.py

@@ -187,7 +187,7 @@ async def _can_join_restricted_room(
 
         Args:
             state_ids: The state of the room as it currently is.
-            room_id: The room being joined.
+            room_version: The room version of the room being joined.
             user_id: The user joining the room.
 
         Returns: