Community, topic and group moderation about activitypub-docs

[cpmoser]

@guysoft I think a Forum is essentially a multiuser Actor. So when you post to the forum, you're essentially posting to the Forum's outbox. The forum is then a larger part of a larger Community ecosystem which passes around content via the context field.

This also means that the Forum should contain its own users and permissions system (ability to post, edit, delete, etc.), and then a moderator on that instance can delete content from that instance (including content replicated from other instances). This means that the forum can share its moderation with other forum instances, through a separate activity feed that other instances would follow.