readme: insert missing information in `Enabling HTTPS support`
readme: insert missing information in `Enabling HTTPS support`

youhong316/docker-gitlab-ci,adiferd/docker-gitlab-ci,sameersbn/docker-gitlab-ci,adiferd/docker-gitlab-ci,sameersbn/docker-gitlab-ci,bboehmke/docker-gitlab-ci,youhong316/docker-gitlab-ci,bboehmke/docker-gitlab-ci