Documentation/ko_KR: update maintainer information

Maintainer informations of Documentation/ko_KR is outdated. This commit
update the informations to the latest ones.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>