Update README.md

Co-authored-by: Simran <Simran-B@users.noreply.github.com>

Author: wi5nia

README.md

@@ -1,6 +1,6 @@
 ## GitHub Docs <!-- omit in toc -->
 
-This repository contains the documentation website code and Markdown source files for [docs.github.com](docs.github.com).
+This repository contains the documentation website code and Markdown source files for [docs.github.com](https://docs.github.com).
 
 GitHub's Docs team works on pre-production content in a private repo that regularly syncs with this public repo.