Merge branch '512505-docs-dora-headings' into 'master'

Edit headings on DORA docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/179887



Merged-by: Lorena Ciutacu <lciutacu@gitlab.com>
Reviewed-by: Ashraf Khamis <akhamis@gitlab.com>
Reviewed-by: Lorena Ciutacu <lciutacu@gitlab.com>