Add in username help text

app/views/projects/mirrors/_instructions.html.haml

@@ -3,6 +3,7 @@
     %li
       = _('The repository must be accessible over <code>http://</code>,
       <code>https://</code>, <code>ssh://</code> and <code>git://</code>.').html_safe
+    %li= _('Include the username in the URL if required: <code>https://username@gitlab.company.com/group/project.git</code>.').html_safe
     %li= _('The update action will time out after 10 minutes. For big repositories, use a clone/push combination.')
     %li= _('The Git LFS objects will <strong>not</strong> be synced.').html_safe
     %li