Translation sustainability via SecureDrop users

Bonjour,

During IFF Giovanni Pellerano gave a wise advice: localization is not sustainable in a given language unless you have at least one user in this language. It also is common sense but I did not think about it before. As it turns out, I think SecureDrop currently supports more languages than what people actually use and this will eventually create problems to keep the translations up to date.

What about we add to the i18n documentation something like: A new language is merged if the administrator of at least one SecureDrop instance declare they will use it ?

What do you think?