[WordPress Plugin] WPML - zh-hans를 cn으로 변경하는 방법

https://wpml.org/forums/topic/can-i-change-zh-hans-to-zh-or-cn-something/

https://wpml.org/forums/topic/change-language-directory-name/#post-1223663

https://wpml.org/forums/topic/sub-folder-name-change/

https://wpml.org/documentation/support/editing-wpmls-languages-table/