Increase SEO for JupyterHub documentation

I was looking for more information about Jupyter support in GitLab, and I found it is not easy to get links to the existing documentation if you search with google.

I tried different combinations, with no success:

gitlab jupyter
gitlab jupyter notebooks
gitlab jupyterhub

There are results about issues, but not to docs. This is probably due to the fact that we call Runbooks in the page. This is totally true, but probably the term is more generic and people may search for jupyter instead.

We could consider how to improve SEO and have documentation results listed.