it does look like there is still a meta-data reference to Google+ in the source btw:
$ curl http://ubuntustudio.org/news/ | grep -i google
<link rel='publisher' href='https://plus.google.com/102125777892703446963' />
Probably leftover from when Google used Google+ profiles for its Google Search authorship snippets.
ah, I see there is already a link to Mastodon under the Community heading, but its link is missing an @ before the profile name:
Mastodon.ART — Your friendly creative home on the Fediverse! Interact with friends and discover new ones, all on a platform that is community-owned and ad-free. Admin: @Curator. Moderators: @EmergencyBattle, @ScribbleAddict, @TapiocaPearl, @Otherbuttons, @katwylder