ko_KR/HOWTO: Add whitespace between URL and text

Because few sentences has no whitespace between URL and text, few
document viewers fail to properly parse the URL from it.  This commit
adds whitespace between them to fix the problem.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>