Add list of versions

From @ckreibich on Slack:

> For similar reasons it would be good to see the version history (that's basically all git tags of the form vX.Y.Z, with the "v" and ".Z" being optional). This would be handy to see because if for some reason the latest version does not work, it helps to know which earlier versions are available to try. (You otherwise have to dig into the repo to find out.)