Add a confirmation for minikube delete

[javajon]

After executing minikube delete namespace <foo> the command ignored the extra parameters and indeed deleted the Minikube instance.

Of course, that was wrong as I meant to issue kubectl delete namespace <foo>. But, it's too late and my error is not recoverable or undoable.

Given that minikube delete is a permanent action (visualize death star) and can easily be substituted with the less destructive kubectl delete x perhaps an added safeguard confirmation for delete might be appreciated.

[r2d4]

This makes sense. We should probably ensure that minikube delete either takes no args or just the machine name