Add LICENSE file and COC to repoistory

[sdake]

Hello,

I noticed that your project has a ASL2 license as per Cargo.toml although there is no LICENSE file in the repository.

There also doesn't appear to be a code of conduct, or other standard documentation.

Thank you,
-steve

[Luap99]

LICENSE file is included since the first commit in this repo: https://github.com/containers/aardvark-dns/blob/main/LICENSE

As for the CoC the general containers one applies: https://github.com/containers/common/blob/main/CODE-OF-CONDUCT.md
We properly should add a link in the repo for that.