Merge branch 'docs/add_autodevops_demo' into 'master'

Add link to Auto DevOps demo video

See merge request gitlab-org/gitlab-ce!29528

doc/topics/autodevops/index.md

@@ -14,6 +14,8 @@ with minimal configuration. Just push your code and GitLab takes
 care of everything else. This makes it easier to start new projects and brings
 consistency to how applications are set up throughout a company.
 
+For a demonstration of Auto DevOps, watch the video [GitLab Auto DevOps demo](https://youtu.be/4Uo_QP9rSGM).
+
 ## Enabled by default
 
 Starting with GitLab 11.3, the Auto DevOps pipeline is enabled by default for all