security.debian.org for Asia region

Thanks to DSAs' deployment, now there is security.debian.org mirror in Japan. It means users who live in Asia/Pacific region are not annoyed with slow download speed for stable security update - anymore :)

New security.debian.org mirror is kindly hosted by Sakura Internet, Inc. (さくらインターネット株式会社) as well as debian-mirror.sakura.ne.jp mirror server in Ishikari, Hokkaido (北海道石狩市).

Kudos to Sakura Internet! (twitter: CEO Kunihiro Tanaka and PR)

note: it's not for Pacific region, only Asia region. Thanks to Paul Wise for pointed out. But still good for our users :)