Add a how-to translate documentation

[fflorent]

It may be helpful for new translator to have a page that describe the process for translating, that explains the prerequisites (having a Github account) and how to translate using Git Localize.

Also see the translation documentation for grist-core: https://github.com/gristlabs/grist-core/blob/main/documentation/translations.md

I just wonder whether we should publish it in the website (https://support.getgrist.com) or leave it on the Github repository.

[fflorent]

My opinion: I tend to prefer having the "how-to translate" documentation published on the website.

Not much for having it localized (we may expect new translators to read contents in English), but rather for letting the user discover they can help translate in their own language (say Ukrainian content does not exist yet and a reader discover that they can help translate to that language).

What do you think?

[lusebille]

Blocked by gitlocalize