Fix the probe for kubernetes example

[afbjorklund]

Need to use "sudo kubectl" now, to get the config...

It was hanging forever, trying to run kubectl version:

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.1", GitCommit:"86ec240af8cbd1b60bcc4c03c20da9b98005b92e", GitTreeState:"clean", BuildDate:"2021-12-16T11:41:01Z", GoVersion:"go1.17.5", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server localhost:8080 was refused - did you specify the right host or port?

The config was moved to be root-only, in a5427dd

/root/.kube/config

Add some descriptions, instead of just "user probe".

INFO[0028] [hostagent] Waiting for the optional requirement 1 of 5: "systemd must be available" 
INFO[0028] [hostagent] Waiting for the optional requirement 2 of 5: "containerd binaries to be installed" 
INFO[0028] [hostagent] Waiting for the optional requirement 3 of 5: "kubectl to be installed" 
INFO[0028] [hostagent] Waiting for the optional requirement 4 of 5: "kubeadm to be completed" 
INFO[0028] [hostagent] Waiting for the optional requirement 5 of 5: "kubernetes cluster to be running" 

Closes #535

[jandubois]

LGTM