Documentation for 'default:' in .gitlab-ci.yml
Write docs for https://gitlab.com/gitlab-org/gitlab-ce/issues/62732. MR that implements it in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24627.
Write docs for https://gitlab.com/gitlab-org/gitlab-ce/issues/62732. MR that implements it in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24627.