FAQ:Why kube-dns vs coredns (#400)

* add FAQ:Why kube-dns vs coredns

* add tags to title for kube-dns vs coredns

* Update why-kube-dns-vs-coredns.md

Co-authored-by: Erik Osterman <erik@cloudposse.com>

content/faq/why-kube-dns-vs-coredns.md

@@ -0,0 +1,17 @@
+---
+title: "What's the relationship between `kube-dns` and `coredns`?"
+description: "Both `kube-dns` and `coredns` do the same thing. Earlier versions of Kubernetes used `kube-dns`. "
+tags:
+- kube-dns
+- coredns
+- Kubernetes
+---
+
+## Question
+
+What's the relationship between `kube-dns` and `coredns`?
+
+
+## Answer
+
+The `coredns` service went GA in Kubernetes 1.11. It just comes down to what version of k8s is running. Practically speaking, there’s no difference between them. We might refer to `kube-dns` in our documentation, but what we mean to say is the dns controller that ships with the Kubernetes version.