* [chore] Stub /api/v1/announcements implementation
This implements the /api/v1/announcements endpoint by simply returning
an empty array. This indicates there are no instance announcements.
Some clients retrieve this endpoint and get surprised by a 404. It tends
to be harmless, but results in some unnecessary logging when trying to
debug other things.
* [fix] Forgot some swagger
* [fix] Fix swagger some more
