In order to prepare the next update of Heptapod based on Gitlab 16.0. The instance will be unavailable on 2023-10-06 between 19:00 and 23:00 UTC+2
Restores the Atom and RSS links, adds Mattermost and Mastodon.
Done in a rough way, but it works well for me. Tested with Firefox (desktop and mobile).
Some advice and/or validation from a web expert will be appreciated.