Merge the following from the English version:
1.223 -> 1.232 doc/ja_JP.eucJP/books/porters-handbook/book.sgml
Submitted by: Hiroo Ono <hiroo _at_ jp dot FreeBSD dot jp>
Refiewed by: Yoshihiro Hosaka <hosaka dot yoshihiro _at_ gmail dot com>
ryusuke
References : [doc-jp-work 1630, 1652, 2122, 2128, 2129, 2131]