gitlab-backup: add page (#19746)

Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>
Co-authored-by: Managor <42655600+Managor@users.noreply.github.com>

pages/common/gitlab-backup.md

@@ -0,0 +1,21 @@
+# gitlab-backup
+
+> Manage backups for a GitLab Omnibus installation.
+> See also: `gitlab-ctl`, `gitlab-runner`.
+> More information: <https://docs.gitlab.com/administration/backup_restore/backup_gitlab/>.
+
+- Create a full backup (default strategy):
+
+`sudo gitlab-backup create`
+
+- Create a full backup using the copy strategy:
+
+`sudo gitlab-backup create STRATEGY={{copy}}`
+
+- Restore a backup by specifying its ID:
+
+`sudo gitlab-backup restore BACKUP={{backup_id}}`
+
+- Restore a backup while skipping specific components:
+
+`sudo gitlab-backup restore BACKUP={{backup_id}} SKIP={{db,uploads,...}}`