kubeadm: update info about CoreDNS in kubeadm-init.md

Add info to install kube-dns instead of CoreDNS, as CoreDNS
is the default DNS server in 1.11.

Add notes that kubeadm config images can be used to list and pull
the required images in 1.11.

content/en/docs/reference/setup-tools/kubeadm/kubeadm-init.md

@@ -79,14 +79,15 @@ following steps:
 
    See [kubeadm join](/docs/reference/setup-tools/kubeadm/kubeadm-join/) for additional info.
 
-1. Installs the internal DNS server (kube-dns) and the kube-proxy addon components via the API server. If kubeadm is invoked with --feature-gates=CoreDNS=true, then [CoreDNS](https://coredns.io/) will be installed as the default internal DNS server instead of kube-dns.  
+1. Installs a DNS server (CoreDNS) and the kube-proxy addon components via the API server.
+   In Kubernetes version 1.11 and later CoreDNS is the default DNS server.
+   To install kube-dns instead of CoreDNS, kubeadm must be invoked with `--feature-gates=CoreDNS=false`.
    Please note that although the DNS server is deployed, it will not be scheduled until CNI is installed.
 
 1. If `kubeadm init` is invoked with the alpha self-hosting feature enabled,
    (`--feature-gates=SelfHosting=true`), the static Pod based control plane is
    transformed into a [self-hosted control plane](#self-hosting).
 
-
 ### Using kubeadm init with a configuration file {#config-file}
 
 {{< caution >}}
@@ -438,7 +439,14 @@ Here `v1.8.x` means the "latest patch release of the v1.8 branch".
 
 `${ARCH}` can be one of: `amd64`, `arm`, `arm64`, `ppc64le` or `s390x`.
 
-If using `--feature-gates=CoreDNS=true` image `coredns/coredns:1.0.2` is required (instead of the three `k8s-dns-*` images).
+If you run Kubernetes version 1.10 or earlier, and if you set `--feature-gates=CoreDNS=true`,
+you must also use the image `coredns/coredns:1.0.2`, instead of the three `k8s-dns-*` images.
+
+In Kubernetes 1.11 and later, you can list and pull the images using the `kubeadm config images` sub-command:
+```
+kubeadm config images list
+kubeadm config images pull
+```
 
 ### Automating kubeadm