Add example showing how to upgrade k8s version
Add example showing how to upgrade k8s version

Stop-gap solution for #6122 until we have a separate page which discusses how to upgrade a minikube cluster.
kubernetes/minikube,kubernetes/minikube,kubernetes/minikube,dalehamel/minikube,dalehamel/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,kubernetes/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,dalehamel/minikube