add another CNAME to get back to the head node

Change-Id: Iac5f61fb161e67d133fbf3992a223d1713492b77
diff --git a/roles/maas/files/update_dns_template.sh b/roles/maas/files/update_dns_template.sh
index 9083520..daa8a76 100755
--- a/roles/maas/files/update_dns_template.sh
+++ b/roles/maas/files/update_dns_template.sh
@@ -60,6 +60,7 @@
 docker-registry CNAME $HOSTNAME
 apt-cache CNAME $HOSTNAME
 mavenrepo CNAME $HOSTNAME
+juju-head-node CNAME $HOSTNAME
 \$INCLUDE "/etc/bind/maas/cnames.inc"
 {{endif}}
 EOT