[README] [Citing] Provide a BibTeX database entry

[kevinmatthes]

Some projects, like SuperCages, provide a separate BibTeX database entry in order to ensure the intended style of citing.

The referenced project provides it in the README.

Since our README.md also contains a citing guideline, I would like to ask if we rather should

• provide a BibTeX entry as a separate file in the repository (e. g. in the support or doc directory) and reference it in the README.md additionally.
• provide the BibTeX entry's source code in our README.md.
• do both (separate file in repository and source code in README.md).

This would make citing this project in the intended form easier since interested users could use these prepared BibTeX database entries as a utility therefore.

What do you think about this?

[michaelquellmalz]

Since it is jor just one reference, we could easily add it to the readme.

[michaelquellmalz]

Done.