api/instances: Include the stats from the /about/more page (#4074)
api/instances: Include the stats from the /about/more page (#4074)

To be able to pull some basic statistics from a Mastodon instance, include the
user, status and connected domain counters in the `/api/v1/instance` response.

Fixes #3570.

Signed-off-by: Gergely Nagy <6780fac3b38619ac20422286e4110a70dbba2203@madhouse-project.org>
Arukas/mastodon,Arukas/mastodon,Arukas/mastodon,Arukas/mastodon