Allow easy k0sctl managed way passing `--profile` for workers

[till]

Hey — first off, thanks for creating k0s and k0sctl. It's been really nice so far.

I had a question about the worker profiles (mostly because of #107). It seems that when I create a profile, I have to add it to installFlags. At least this was what made it work. Should I pr a note to the docs here or to the k0s repository?

[till]

Also related: #309

[till]

A bit more, #309 includes snippets of what needs to happen, in addition:

• you need to create the directories yourself
• you need to chown them (e.g. on the controller: kube-apiserver:kube-apiserver, worker: root:root)

Not sure if that should (or could) be "addressed" in k0sctl? Happy to attempt PRs.

[kke]

Yes worker profiles aren't understood by k0sctl so you need to use the --profile installFlag. Maybe this could be implemented so it would become a configuration setting.