Enrich CITATION.cff with additional bio.tools metadata

[supernord]

Extending the work completed in this PR #29

And considering the ideas raised in this issue: #34

[supernord]

Additional fields that might be added to the CITATION.cff, possibly by modifying gen_citation_cff.py?

• https://github.com/citation-file-format/citation-file-format/blob/1.2.0/schema-guide.md#keywords
• https://github.com/citation-file-format/citation-file-format/blob/1.2.0/schema-guide.md#license
• https://github.com/citation-file-format/citation-file-format/blob/1.2.0/schema-guide.md#abstract