Add GitLab contact email link also to services overview page

* Add the contact email link for GitLab inquiries to the GitLab Services
overview page.

_layouts/services/index.html

@@ -118,7 +118,7 @@
                                 <a href="{{ 'services/helmholtzgitlab' | relative_url }}"><strong>More...</strong></a>
                             </p>
                             <h4>Talk to us</h4>
-                            {% include contact_us/mini.html %}
+                            {% include contact_us/mini.html contact_mail_link=site.contact_mail_for_gitlab %}
                             {% include helpdesk/mini.html %}
                         </div>
                         <img