Add template CFF

[tobyhodges]

Closes #508

Adds a template CITATION.cff file to be included in new lessons initialised with create_lesson(). I had a go at writing tests, and would love feedback on what I missed and how I could have done it better.

[sdruskat]

I like the sparsity of the CFF template.
Would it make sense to include repository-code in this as well, to record the lesson development repo?
Could completing the field even be automated when the user interacts with, e.g., GitHub? 🤷

[tobyhodges]

Thanks @sdruskat I had considered adding this field, and other fields I would recommend such as identifiers, but in the end opted for a "minimum viable lesson CFF". I am trying to supplement this template content with documentation elsewhere (e.g. in the Collaborative Lesson Development Training curriculum and the Workbench docs).

TBH we are also still figuring out exactly what guidance we want to give the community about the information they put into their CFFs: creating them is the easy part, but updating them as the lesson develops and matures is more tricky...

I'm afraid the kind of automated filling of information you mentioned is not possible right now, but would indeed be a cool development for the future.

[ocaisa]

One thing I've asked is how do we cross-reference to another CFF (adding tons of authors would make this cumbersome). I got a response for this in citation-file-format/citation-file-format#538 (comment) which I think may be useful (CI is one option, reference to the CFF file directly is another)

[tobyhodges]

Thanks @ocaisa. I guess I need to open a new issue somewhere to keep track of what advice we should give people about CFF, which would include your suggestion. I think docs.carpentries.org is the appropriate place.

[froggleston]

Looks great! 🚀