Merge branch 'mgibsongl-auto-merge-steps' into 'master'

Add missing step to auto-merge instructions

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/127254



Merged-by: Russell Dickenson <rdickenson@gitlab.com>
Approved-by: Russell Dickenson <rdickenson@gitlab.com>
Co-authored-by: Michael Gibson <mgibson@gitlab.com>