Merge branch 'cb-pg-16-default-docs' into 'master'

Announce PostgreSQL 14 and 15 deprecation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182866



Merged-by: Evan Read <eread@gitlab.com>
Approved-by: Martin Brümmer <mbruemmer@gitlab.com>
Approved-by: Denis Afonso <dafonso@gitlab.com>
Approved-by: Evan Read <eread@gitlab.com>
Reviewed-by: Clemens Beck <cbeck@gitlab.com>
Co-authored-by: Clemens Beck <cbeck@gitlab.com>
Co-authored-by: Peter Lu <plu@gitlab.com>