Remove files specific to JOSE paper submission

[JaroCamphuijsen]

It seems there are some files in the repository that were generated only for the purpose of the publication in the JOSE journal (e.g. paper.md and paper.bib)
They currently have no actual role in the lesson and are confusing because they contain duplication of information (e.g. authorlist and descriptions).

I'd like to suggest to remove them from the repository and tag the version that was used for the paper submission with an understandable tag (e.g. JOSE-submission).

[douglowe]

Requirement for submission to JOSE for getting the lesson onto Carpentries Lab. See carpentries-lab/reviews#30 and https://openjournals.readthedocs.io/en/jose/submitting.html#how-to-prepare-a-learning-module-submission

[douglowe]

Aleks will check if this is still a req