New feature as of Discourse 2.8.0 beta 9 — tags can now have descriptions. You will see that description if you hover over the tag by the topic title. (Try it with “audio”, or “meta” on this post.
I don’t personally plan on an effort to describe all tags, but if someone else feels inspired, go for it. Also, if you have a particular tag that seems like it’d benefit from an explanation — like for this situation https://discussion.fedoraproject.org/t/whats-a-good-tag-for-fedora-infrastructure-related-topics/62230 , reply here. Use the format
#tag: Suggested description
in your replies, and the moderators can check off those suggestions as they’re applied, like
#tag: Suggested description
I’ll also set this up to auto-delete replies in a month, so it doesn’t get long. The history will be in the active tag descriptions.