Merge branch 'rlehmann1-docker-install-edits3-docs' into 'master'

Rename backup_restore.md and edit remaining pages

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/167963



Merged-by: Suzanne Selhorn <sselhorn@gitlab.com>
Co-authored-by: Ryan <rlehmann@gitlab.com>