Clarify that the creation event can have other keys in it

api/client-server/create_room.yaml

@@ -151,18 +151,10 @@ paths:
                 title: CreationContent
                 type: object
                 description: |-
-                  Extra keys to be added to the content of the ``m.room.create``.
-                  The server will clobber the following keys: ``creator``. Future
-                  versions of the specification may allow the server to clobber
-                  other keys.
-                properties:
-                  "m.federate":
-                    type: boolean
-                    description: |-
-                      Whether users on other servers can join this room. Defaults
-                      to ``true`` or what the server specifies. Setting this to 
-                      ``false`` may prevent users from being invited as part of
-                      this room creation request if they reside on other servers.
+                  Extra keys, such as ``m.federate``, to be added to the content
+                  of the `m.room.create`_ event. The server will clobber the following
+                  keys: ``creator``. Future versions of the specification may allow
+                  the server to clobber other keys.
               initial_state:
                 type: array
                 description: |-