Make support workflow links absolute

Merged username-removed-444214 requested to merge absolute-links into master

Fixes https://gitlab.com/gitlab-com/www-gitlab-com/issues/1258

The update of middleman in https://gitlab.com/gitlab-com/www-gitlab-com/commit/aab9676aea985eb8ef36ab1b3d6eef000acbb488 broke the link_to method for absolute links. Simple fix is to add /