clarify that k3s-root is not pure "apache-2" licensed

[dirkmueller]

My understanding is that the license declaration is just for the k3s-root specific part, not for the embedded components like busybox. we could be more careful and specify GPLv2?

[brandond]

The things in the repo (build scripts and config files) are covered by the license; I don't think we're making any claims about the software produced by running the build scripts. Is that the gap you're trying to address?

[dirkmueller]

Yes, exactly. I think we should be clarifying that the license only covers the build scripts, not the software that those build scripts are building. I think an README.md could cover it.