To publish to GitLab pages, all that is required is to provide a CI job
that creates files in a directory called "public" and list that as an
artifact.

When the CI job completes, the website is immediately available at the
URL  https://username.gitlab.io/reponame

. This makes it much easier to
preview changes to the site than with OpenShift apps.

Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>