Docs: Update all links to relative in /workflow and /administration

doc/administration/auth/google_secure_ldap.md

doc/administration/compliance.md

doc/administration/custom_hooks.md

doc/administration/geo/disaster_recovery/planned_failover.md

doc/administration/geo/replication/database.md

doc/administration/geo/replication/external_database.md

doc/administration/geo/replication/high_availability.md

doc/administration/geo/replication/index.md

doc/administration/geo/replication/tuning.md

doc/administration/high_availability/img/geo-ha-diagram.png

doc/administration/high_availability/nfs.md

doc/administration/incoming_email.md

doc/administration/index.md

doc/administration/operations/fast_ssh_key_lookup.md

doc/administration/packages.md

doc/administration/raketasks/project_import_export.md

doc/workflow/README.md

doc/workflow/gitlab_flow.md

doc/workflow/lfs/migrate_from_git_annex_to_git_lfs.md

doc/workflow/merge_request_approvals.md