Add instructions for cytosim

https://community.france-bioinformatique.fr/t/request-for-configuring-a-different-version-of-cytosim/4477/8?u=lgueguen

Contributor checklist

• This tool is not an isolated library that could be installed manually by a user or that should be included in a langage package (Python, R, Perl, etc.)
• The conda env or apptainer definition could be rerun at any time and would result in the exact same tool version

Please, review our Best pratices for more informations