docs: Add CITATION.cff Citation File Format file

[matthewfeickert]

Resolves #413

• Add Citation File Format file to repo to get repository cite button on GitHub and citation support on Zenodo.
  • c.f. https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-citation-files

For additional context and examples c.f. scikit-hep/pyhf#1551

The schema used is validated by cffconvert

$ pipx install cffconvert
$ cffconvert --validate --infile CITATION.cff 
Citation metadata are valid according to schema version 1.2.0.

[matthewfeickert]

@LovelyBuggies can you please confirm that this information is correct? Also, do you have an ORCID?

[matthewfeickert]

This is the version agnostic Zenodo DOI https://doi.org/10.5281/zenodo.4057112

[matthewfeickert]

Preview of what this looks like on the repo page:

[matthewfeickert]

I'm of the opinion that including the version number in software citation is highly important, but this does mean that someone then needs to start keeping this synced or use a bump tool like pyhf does. I can understand that might not be desirable.

[matthewfeickert]

It was pointed out by @jpivarski, @alexander-held, and @cranmer today in the IRIS-HEP Analysis Systems meeting that adding detailed version information like this is probably more of a harm than a benefit.

• Adding the detailed version information but then linking to the general DOI is perhaps inconsistent behavior.
• Having the version information to help out the people getting the citation is also assuming that people are going to be updating the version of the citation file (e.g. BibTeX file) every time they use it in a paper, which in reality is probably naive on my part given how many people have BibTeX files that they just copy from project to project.

Given this I'm going to remove the v2.6.1 information and make the CITATION.cff file more similar to Awkward's.

[henryiii]

IMO a guide should be added to scikit-hep.org, probably under developer. Maybe could be combined in an "extras" page that covers license, badges, etc?