Consolidate language lists across repos

[tesseralis]

Currently, we keep three separate lists of languages:

• The one in this repo in the langs/ folder
• The one in Is React Translated Yet
• The "official" one in the reactjs.org repo

Whenever a language is created, I have to update all three of this sources. When one is finished, I need to update the official React list too. I'd like to automate some of this.

[mfazza]

What would a good solution to this look like? A script to run with node using github's API?