I suggest Tor Project adds information about which Debian/Ubuntu versions are supported to relay setup guide. Currently Support/Getting Started/Installation has no mention about this, the only place with this information is the bridge setup guide and it incorrectly listed bionic, cosmic, disco, eoan, and focal as supported Ubuntu version (none of them are).
Reason: Saw this post and when looking up for guides setting up relays I can’t find any info about supported Ubuntu versions.