Handle CITATION.md and other files that GitHub supports

[mhucka]

Turns out that GitHub supports more than just CITATION.cff. We should be able to handle some of these others as well, if a repo lacks a CITATION.cff file.

https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-citation-files#other-citation-files

[tmorrell]

GitHub doesn't attempt to parse those files into their component metadata, they just link to them. We can certainly add links to those files, but I don't think we should try to extract metadata from them.

[mhucka]

Yeah, I don't think we can parse them; rather, I was thinking that if the repo doesn't have a CITATION.cff but does have, say, a CITATION.bib, we could feed that to the current bibtex conversion code and add the result to the references field in the metadata record.

[tmorrell]

Yeah, that would work. Wouldn't show up anywhere at the moment...but eventually that would be a reasonable parsing of .bib files