I noticed that the language code for Korean is currently listed as kr, but this is not correct.

According to the ISO 639-1 standard, the correct two-letter code for Korean is ko.
(kr is a country code for South Korea in ISO 3166, not a language code.)

Reference: https://en.wikipedia.org/wiki/ISO_639-1

Contributors of #429

@dodok8 @baekrang256 @2paperstar

Can you confirm this?