Headscale dropped docker tag for headscale:latest

[KenyOS]

I was following the guide on readme and I found error while docker-compose pull the latest tag on headscale docker image, and I found the reason below the explanation. From now on.. stable version should be tagged on release version.

juanfont/headscale#1810

[routerino]

I definitely don't agree with their reasoning behind dropping the latest tag, saying it's "not best practice" seems more of a "we goofed the latest tag convention and so we're going to blame the tag instead of using it right".

That said, yes, I'll update the blog and readme :).

[routerino]

Fixed the readme up in #154