Merge branch 'ctrt-heading-level' into 'master'

Change h3 headings to h4 in "Change your SAML app"

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/115391



Merged-by: Suzanne Selhorn <sselhorn@gitlab.com>
Co-authored-by: Jonathan Glassman <jglassman@gitlab.com>