Add m.room.redacted in events list

docs/specification.rst

@@ -968,6 +968,22 @@ prefixed with ``m.``
     ``read`` (sent when the event has been observed by the end-user). The ``target_event_id``
     should reference the ``m.room.message`` event being acknowledged. 
 
+``m.room.redaction``
+  Summary:
+    Indicates a previous event has been redacted.
+  Type:
+    Non-state event
+  JSON format:
+    ``{ "reason": "string" }``
+  Description:
+    Events can be redacted by either room or server admins. Redacting an event means that
+    all keys not required by the protocol are stripped off, allowing admins to remove
+    offensive or illegal content that may have been attached to any event. This cannot be
+    undone, allowing server owners to physically delete the offending data.
+    There is also a concept of a moderator hiding a non-state event, which can be undone,
+    but cannot be applied to state events.
+    The event that has been redacted is specified in the ``redacts`` event level key.
+
 m.room.message msgtypes
 -----------------------
 Each ``m.room.message`` MUST have a ``msgtype`` key which identifies the type of