Merge pull request #2952 from scality/coredns-typo

Fix `coreos_dual` -> `coredns_dual` typo

roles/docker/tasks/set_facts_dns.yml

@@ -26,7 +26,7 @@
 - name: add upstream dns servers (only when dnsmasq is not used)
   set_fact:
     docker_dns_servers: "{{ docker_dns_servers + upstream_dns_servers|default([]) }}"
-  when: dns_mode in ['kubedns', 'coredns', 'coreos_dual']
+  when: dns_mode in ['kubedns', 'coredns', 'coredns_dual']
 
 - name: add global searchdomains
   set_fact: