Document recent breaking changes for CI Steps

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/170817



Merged-by: Marcel Amirault <mamirault@gitlab.com>
Approved-by: Marcel Amirault <mamirault@gitlab.com>
Reviewed-by: Marcel Amirault <mamirault@gitlab.com>
Co-authored-by: Cameron Swords <cswords@gitlab.com>