Remove some NFS references from documentation

doc/administration/backup_restore/backup_gitlab.md

doc/administration/geo/replication/datatypes.md

doc/administration/gitaly/configure_gitaly.md

doc/administration/gitaly/gitaly_geo_capabilities.md

doc/administration/gitaly/index.md

doc/administration/gitaly/praefect.md

doc/administration/monitoring/performance/performance_bar.md

doc/administration/nfs.md

doc/administration/sidekiq/index.md