HOWTO ja_JP sync

Attached is Documentation/ja_JP/HOWTO sync patch for 3.10.
This patch was reviewed by Japanese translation community called JF.

Signed-off-by: Tsugikazu Shibata <tshibata@ab.jp.nec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>