Document http://www.w3.org/ns/pim/meeting#LongChatInvite

[michielbdejong]

We should document the use of http://www.w3.org/ns/pim/meeting#LongChatInvite in https://github.com/SolidOS/solid-logic/blob/9c5e74c1bceafa0802f6adbd6760e7e7b6f22702/src/chat/chatLogic.ts#L193.

[mrkvon]

Additionally, it doesn't seem to be clear how the chat owner can keep track of the invitees. One option is to check in chat root .acl for agents with append access. Or use some predicate in chat channel.

[michielbdejong]

It's also possible that some people have access to append to the 'today' file but not to be the first to say good morning on a new day. Maybe we should document that as an anti-pattern

Cc @jaxoncreed who just completed the Solid Data Module for chat.