Added GitHub citation file

[lobis]

Adds citation file according to https://docs.github.com/es/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-citation-files to allow for "Cite this repository" menu in front page.

Data taken from https://doi.org/10.1016/j.cpc.2021.108281, @rest-for-physics/all feel free to add any additional details.

[juanangp]

I have nothing against this PR, but just to let you know you can also cite via zenodo https://zenodo.org/record/6487675#.YnVXwtrP1PY

[juanangp]

I have nothing against this PR, but just to let you know you can also cite via zenodo https://zenodo.org/record/6487675#.YnVXwtrP1PY

I see, it is linked to the cff file, so we have to update this file when we launch a new release? Or this can be somehow automated?

[jgalan]

I have nothing against this PR, but just to let you know you can also cite via zenodo https://zenodo.org/record/6487675#.YnVXwtrP1PY

I see, it is linked to the cff file, so we have to update this file when we launch a new release? Or this can be somehow automated?

In principle, there is a zenodo ID to cite all versions

[10.5281/zenodo.4528985](https://doi.org/10.5281/zenodo.4528985).

[jgalan]

Before merging I would allow a couple of days to allow other authors to add their ORCID id.