ynh_use_logrotate documentation misleading/wrong

[chri2]

This documentation https://yunohost.org/en/packaging_apps_scripts_helpers#ynh-use-logrotate doesn't mention these conditions.

[tituspijean]

To be added in the header comments of the function for automagic documentation generation: https://github.com/YunoHost/yunohost/blob/7d0d82ae016ae3e7cdb06423b67678d7f7a5d9ca/helpers/logrotate#L5-L14