Revision 1 - Edit and delete your messages

[jorge-campo]

@shamisem , FYI only - We need to include in the revision information about owners and admin deleting messages in the community.

Owners and admins can delete any message, not only their messages (see https://help.status.im/en/status-communities/permissions-by-role-in-status-communities/). Creating a new "delete messages" topic for admins and owners is not worth it.

Feel free to take care of this revision. I leave it unassigned in case someone else wants to do it.

[jorge-campo]

Updates #249.