Mention prerequisites for building the iso images.
Mention prerequisites for building the iso images.

Add the tools that I had missing. Also describe minimal gpg2 setup.

abbytiz/minikube,endocode/minikube,mikegrass/minikube,mikegrass/minikube,endocode/minikube,warmchang/minikube,kubernetes/minikube,cu12/minikube,skipjaq/minikube,dlorenc/minikube,dongsupark/minikube,dalehamel/minikube,skipjaq/minikube,dalehamel/minikube,kubernetes/minikube,cu12/minikube,warmchang/minikube,cu12/minikube,endocode/minikube,r2d4/minikube,abbytiz/minikube,dims/minikube,dongsupark/minikube,aaron-prindle/minikube,kubernetes/minikube,dlorenc/minikube,r2d4/minikube,dlorenc/minikube,aaron-prindle/minikube,abbytiz/minikube,dlorenc/minikube,warmchang/minikube,dims/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,dlorenc/minikube,aaron-prindle/minikube,warmchang/minikube,dlorenc/minikube,dlorenc/minikube,dims/minikube,dalehamel/minikube,warmchang/minikube,dongsupark/minikube,r2d4/minikube,skipjaq/minikube,dlorenc/minikube,mikegrass/minikube,kubernetes/minikube,kubernetes/minikube,kubernetes/minikube