Documentation: HOWTO: Updates on subsystem trees, patchwork, -next (vs. -mm) in ko_KR

The update did not applied on Korean translation although it applied on
English documentation. Apply it on Korean translation now.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>