Add direct link to GitHub tag

[timwoj]

From @ckreibich on Slack:

When looking at a particular package, you're currently showing the latest version in the title, and that's great. One immediate suggestion is that if the repo is on Github (which they basically all are), you could make that clickable so it takes you directly to the repo at that tag. The version always corresponds to a git tag. That's helpful because it can be handy to view the zkg.meta at that version quickly.