Add feature_bridge_state

Author: Half-Shot

docs/labs.md

@@ -88,3 +88,10 @@ An improved dialog for inviting users. Once finished, this will replace both the
 DM creation dialog and the 'invite user' dialog. This is a work in progress and
 as such not all functionality may be present until the feature replaces today's
 UX.
+
+## Bridge info tab (`feature_bridge_state`)
+
+Adds a "Bridge Info" tab to the Room Settings dialog, if a compatible bridge is
+present in the room. The Bridge info tab pulls information from the `m.bridge` state event ([MSC2346](https://github.com/matrix-org/matrix-doc/pull/2346)). Since the feature is based upon a MSC, most
+bridges are not expected to be compatible, and users should not rely on this
+tab as the single source of truth just yet.