create a cname for the local docker registry

Change-Id: I9c8d4415a29ce5fdc532f53194b10f1f022634ee
diff --git a/roles/maas/files/update_dns_template.sh b/roles/maas/files/update_dns_template.sh
index 448d3fc..659a799 100755
--- a/roles/maas/files/update_dns_template.sh
+++ b/roles/maas/files/update_dns_template.sh
@@ -57,6 +57,7 @@
 {{if domain == '$DOMAIN'}}
 \$INCLUDE "/etc/bind/maas/dhcp_harvest.inc"
 $HOSTNAME IN A $LHOST
+docker-registry CNAME $HOSTNAME
 {{endif}}
 EOT