This option serves the same purpose as the existing room_invite_state_types option, which defines what state events are sent over to a user that is invited to a room. This information is necessary for the user - who isn't in the room yet - to get some metadata about the room in order to display it in a pretty fashion in the user's pending-invites list. It includes information such as the room's name, avatar, topic, canonical alias, room encryption state etc. as well as the invite membership event which the invited user's homeserver can reference. This new option is the exact same, but is sent by a homeserver in the room to the knocker during the knock process. This option will actually be utilised in a later commit.
Synapse Documentation
This directory contains documentation specific to the synapse homeserver.
All matrix-generic documentation now lives in its own project, located at matrix-org/matrix-doc
(Note: some items here may be moved to matrix-org/matrix-doc at some point in the future.)