Remove extraneous v11 tag in v12 auth rules (#2199)

* Remove extraneous v11 tag in v12 auth rules

* Changelog to copy #2193

changelogs/room_versions/newsfragments/2199.feature

@@ -0,0 +1 @@
+Add [room version 12](/rooms/v12) as per [MSC4304](https://github.com/matrix-org/matrix-spec-proposals/pull/4304).

content/rooms/v12.md

@@ -131,8 +131,7 @@ The rules are as follows:
         1.  If the event is not validly signed by the homeserver of the user ID denoted
             by the key, reject.
     3.  If `membership` is `join`:
-        1.  {{% changed-in v=11 %}}
-            If the only previous event is an `m.room.create` and the
+        1.  If the only previous event is an `m.room.create` and the
             `state_key` is the sender of the `m.room.create`, allow.
         2.  If the `sender` does not match `state_key`, reject.
         3.  If the `sender` is banned, reject.