Include information on how invite_room_state works
Include information on how invite_room_state works

This is completely optional, and the events included are up to the sender. 

Sources:
* Structure: https://github.com/matrix-org/synapse/blob/d69decd5c78c72abef50b597a689e2bc55a39702/synapse/handlers/message.py#L896-L904
* What events are recommended: https://github.com/matrix-org/synapse/blob/d69decd5c78c72abef50b597a689e2bc55a39702/synapse/config/api.py#L30-L40
matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc