Add translated Japanese man pages to the doc/ directory.

Add translated Japanese man pages to the doc/ directory.

The directory structure for translated manual pages should be :

  doc/<locale>.<encoding>

This nomenclature is used by several other open-source documentation
projects.  These manual pages are current as of DHCP 3.0.1rc8 but they
are not complete.  These man pages only cover the client.

We should add $Id$ tags to the english language documents, so we can
easily see what version of the English document this Japanese document
is current with.

Submitted by:	Kazuo Horikawa <horikawa@FreeBSD.org>