service.md

@@ -41,6 +41,7 @@ complete. This does not include undocumented services, below.
 [backup]: howto/backup
 [cache]: howto/cache
 [dns]: howto/dns
+[documentation]: service/documentation
 [drbd]: howto/drbd
 [ganeti]: howto/ganeti
 [grafana]: howto/grafana