Quick-guide-to-translating-MathJax.md

@@ -5,7 +5,7 @@ If you have any questions, contact us on the issue tracker or the [mathjax devel
 ***
 Here's a quick guide to help you translate MathJax directly here on github.
 
-* Figure out the [language code](https://en.wikipedia.org/wiki/IETF_language_tag) -- let's call this `xx`.
+* Figure out the [IETF language tag](https://en.wikipedia.org/wiki/IETF_language_tag) -- let's call this `xx`. (Note: it could also be a `xx-yy` style language tag.)
 * Fork [the MathJax i18n repository](https://github.com/mathjax/MathJax-i18n)
 * Copy `/JSON/en/` to `/JSON/xx`
 * Replace all `en`s with `xx`s in all files contained in this folder.