Document the existence of `gitlab-ci-rake`
Document the existence of `gitlab-ci-rake`

felixbuenemann/omnibus-gitlab,gitlabhq/omnibus-gitlab,felixbuenemann/omnibus-gitlab,aleksandrs-ledovskis/omnibus-gitlab,aleksandrs-ledovskis/omnibus-gitlab,aleksandrs-ledovskis/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,copystudy/omnibus-gitlab,copystudy/omnibus-gitlab,felixbuenemann/omnibus-gitlab,gitlabhq/omnibus-gitlab,copystudy/omnibus-gitlab