Create new process for someone who wants to add a new language translation

[lwasser]

We should also consider adding a process to start a new language translation: if someone volunteers to work on a new language, who makes the go-ahead decision, designates the translation group/lead, etc.

Back when I wrote the Translation guide for contributors I added a bit of information for the technical steps here but no other guidance.

Originally posted by @flpm in #109 (review)