How do I set a localized name for a folder?

I want to give a folder a localized name. In one of Apple's articles, I found out that the ".localized" file (e.g., in ~/Downloads) is responsible for indicating this, but all of the .localized files are empty (length 0). I can't find any documentation for the content of this file, or even if it can have any at all.

How can I make a folder whose name is "One", but whose Spanish name is "Uno"?