Add a link to GitHub from the Docs

[coliff]

Would be useful to have a link to his repo from the Docs
https://tailwindcss.com/docs/

[MichaelDeBoey]

If you click the version number underneath the logo (top right in the navigation), you'll be redirected to the releases page on this repo 🙂

[adamwathan]

Yeah we need to redesign the docs a bit in general; lots of stuff it doesn't really accommodate yet :/ I'm going to at least add a little GitHub icon under the search for now.