Add docs for room_type arg

Author: KnugiHK

synapse_admin/room.py

@@ -223,6 +223,7 @@ def create(
             members (list, optional): a list of user that should be the members of the room. Defaults to None. # noqa: E501
             federation (bool, optional): can the room be federated. Defaults to True.
             leave (bool, optional): whether to leave the room yourself after the creation. Defaults to False.
+            room_type (str, optional): the type of room. Defaults to None.
 
         Returns:
             RoomInformation: roomid: room id, joined: a list of joined users