Add a citation file

[slotruglio]

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Is your feature request related to a problem? Please describe.
I started an analysis of use feasibility and I used this repository as a starting point and I would like to mention this repository in a proper way.

Describe the solution you'd like
Adding a CITATION.cff like described in Github: About CITATION files.

Describe alternatives you've considered
A possibility is to mention the url in a footnote or creating a own bibtex format. However this solution is not standard, so it's possible to write in a wrong way the citation.

Additional context
Adding this file, the possibility to cite the repository in papers, thesis and articles could increase repository contribution.