Add citation file

[adebardo]

Context

From Sébastien Dinot

It would be useful to make it easier for users (and ourselves) who would like to cite our tool or the related papers.
For this purpose, GitHub (as zenodo and zeroto) supports the CITATION.cff file: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-citation-files

This file is user-friendly.

Tasks

• List the papers related to the project
• Define the preferred citation
• Create and add the CITATION.cff file