Merge branch 'meta-example' into 'master'

Link to the gitlab-ci.yml file of GitLab itself.

I'm hunting for this link from time to time in customer demo's so I think it is useful to add.

/cc @ayufan 

See merge request !1993

doc/ci/README.md

@@ -24,6 +24,7 @@
 ### Examples
++ [The .gitlab-ci.yml file for GitLab itself](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/.gitlab-ci.yml)
 + [Test and deploy Ruby applications to Heroku](examples/test-and-deploy-ruby-application-to-heroku.md)
 + [Test and deploy Python applications to Heroku](examples/test-and-deploy-python-application-to-heroku.md)
 + [Test Clojure applications](examples/test-clojure-application.md)