Docs: article - Deploy SB apps to CF with GitLab CI/CD

What does this MR do?

• Follow-up from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18493
• Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/47505

cc/ @DylanGriffith FYI. For further contributions to the docs, pls finish the MR you started 😉 Thanks!