GitLab

Google OSS policies say to name this "CONTRIBUTING.md".

Change-Id: I037f52a443caacc89868b7c14af91dd3d1b681a9
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/499761

Reviewed-by: Gavin Mak <gavinmak@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>