README: use SQL commands to create user and database in external postgresql database section
README: use SQL commands to create user and database in external postgresql database section

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