Licensing of example .kdl files

[hkolbeck-streem]

It might be nice for folks to have pre-constructed examples to run through tests, but that would likely require copying the (currently) 4 examples provided: nuget.kdl, ci.kdl, website.kdl, and Cargo.kdl into their codebases. Currently that would require their code, at least by my understanding, to be released under the same CC share-alike license as the spec which may not be ideal. I'd suggest taking a dual-licensing approach as I did here: https://github.com/hkolbeck/kdl4j/blob/trunk/LICENSE.md