Differentiate semver tags from everything else

[msiebuhr]

The plan is that whomever can upload some docs about whatever version of what they're working on (git hooks would be ideal here).

In order to make the "official" documentation stand out from all the junk, promote tags that are valid semvers a bit more prominently than everything else. Or show them in entirely different lists.

[msiebuhr]

Possibly VCS-tags like head, master, stable & such should be highlighted as well...