Merge branch 'ls/github' into maint

Help contributors that visit us at GitHub.

* ls/github:
  Configure Git contribution guidelines for github.com

.github/CONTRIBUTING.md

+## Contributing to Git
+
+Thanks for taking the time to contribute to Git! Please be advised that the
+Git community does not use github.com for their contributions. Instead, we use
+a mailing list (git@vger.kernel.org) for code submissions, code
+reviews, and bug reports.
+
+Nevertheless, you can use [submitGit](http://submitgit.herokuapp.com/) to
+conveniently send your Pull Requests commits to our mailing list.
+
+Please read ["A note from the maintainer"](https://git.kernel.org/pub/scm/git/git.git/plain/MaintNotes?h=todo)
+to learn how the Git project is managed, and how you can work with it.
+In addition, we highly recommend you to read [our submission guidelines](../Documentation/SubmittingPatches).
+
+If you prefer video, then [this talk](https://www.youtube.com/watch?v=Q7i_qQW__q4&feature=youtu.be&t=6m4s)
+might be useful to you as the presenter walks you through the contribution
+process by example.
+
+Your friendly Git community!

.github/PULL_REQUEST_TEMPLATE.md

+Thanks for taking the time to contribute to Git! Please be advised that the
+Git community does not use github.com for their contributions. Instead, we use
+a mailing list (git@vger.kernel.org) for code submissions, code reviews, and
+bug reports. Nevertheless, you can use submitGit to conveniently send your Pull
+Requests commits to our mailing list.
+
+Please read the "guidelines for contributing" linked above!