Change the value of resolver in nginx-config.yaml (cortexproject#671)

* Change the value of resolver in nginx-config.yaml since the address of kube-dns changed

* Use kube-dns as resolver

Author: swhsiang

k8s/nginx-config.yaml

@@ -21,7 +21,7 @@ data:
       access_log   /dev/stderr  main;
       sendfile     on;
       tcp_nopush   on;
-      resolver 10.0.0.10;
+      resolver kube-dns.kube-system.svc.cluster.local;
 
       server { # simple reverse-proxy
         listen 80;