It was requested that for this page a couple of methods
should be outlined:
- manual installation for CoreDNS explained at the Kubernetes
section of the GitHub project for CoreDNS
- installation and upgrade via kubeadm
Make the above changes and also add a section "About CoreDNS".
This commit also lowercases a section title.
CoreDNS is installed by default in 1.11.
Add notes on how to install kube-dns instead.
Update notes about CoreDNS->CoreDNS upgrades as in 1.11
the Corefile is retained.
Add example on upgrading from kube-dns to CoreDNS.
Lubomir I. Ivanov