Add private_chat_shared_power

specification/1-client_server_api.rst

@@ -756,15 +756,18 @@ options which can be set when creating a room:
   Optional:
     Yes
   Value:
-    ``private_chat`` or ``public_chat``
+    ``private_chat``, ``private_chat_shared_power`` or ``public_chat``
   Description:
     Convenience parameter for setting various default state events based on a
     preset.
 
-    Two presets are defined:
+    Three presets are defined:
 
     - ``private_chat``: Sets the ``join_rules`` to ``invite`` and
       ``history_visibility`` to ``shared``
+    - ``private_chat_shared_power``: Set the ``join_rules`` to
+      ``invite``, ``history_visibility`` to ``shared`` and gives all invitees
+      the same power level as the creator.
     - ``public_chat``: Sets the ``join_rules`` to ``public`` and
       ``history_visibility`` to ``shared``