README: added note on http -> https redirection with haproxy
README: added note on http -> https redirection with haproxy

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