Merge the following from the English version:
221 -> 223 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>,
hrs, ryusuke
Reference : [doc-jp-work 1602, 2105, 2110, 2111, 2115, 2116, 2117, 2118, 2119,
2120, 2121]