Create CITATION.cff

[iwilltry42]

Discussed in https://github.com/k3d-io/k3d/discussions/1403

^{Originally posted by MacherelR January 29, 2024} Hello everyone,

I'm currently writing my master's thesis, in which I've used k3d as development tool, now in my thesis paper I'd like to cite it, and as there's not "cite this repository" option on this repo I'd like to know whether someone has already cited this in a paper and if yes, what was the bibtex citation ?

Thanks in advance !

Rémy

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