Remove r2d4 from maintainers
Remove r2d4 from maintainers

kubernetes/minikube,warmchang/minikube,warmchang/minikube,kubernetes/minikube,dalehamel/minikube,dalehamel/minikube,dlorenc/minikube,kubernetes/minikube,dlorenc/minikube,dlorenc/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,dalehamel/minikube,dlorenc/minikube,warmchang/minikube,kubernetes/minikube,kubernetes/minikube,dlorenc/minikube,kubernetes/minikube,dlorenc/minikube,dlorenc/minikube,warmchang/minikube,dlorenc/minikube