Add orion to nginx group for zabbix monitoring

Signed-off-by: Florian Pritz <bluewind@xinu.at>

hosts

@@ -33,6 +33,7 @@ luna.archlinux.org
 [nginx]
 apollo.archlinux.org
 luna.archlinux.org
+orion.archlinux.org
 
 [buildservers]
 soyuz.archlinux.org