Merge branch 'update-zoekt-syntax' into 'master'

Update Zoekt syntax documentation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/130508



Merged-by: Ashraf Khamis <akhamis@gitlab.com>
Approved-by: Ashraf Khamis <akhamis@gitlab.com>
Co-authored-by: Dmitry Gruzd <dgruzd@gitlab.com>