Merge the following from the English version:

1.40 -> 1.51 Makefile
1.2 -> 1.3 chapter.decl
1.15 -> 1.19 chapters.ent
1.106 -> 1.118 book.sgml [doc-jp 8394]
1.38 -> 1.45 backups/chapter.sgml [doc-jp 8394]
1.458 -> 1.468 contrib/chapter.sgml [doc-jp 8430]
1.26 -> 1.27 disks/chapter.sgml [doc-jp 8402]
1.41 -> 1.63 introduction/chapter.sgml [doc-jp 8386]
1.139 -> 1.165 mirrors/chapter.sgml [doc-jp 8431]
(new) -> 1.4 config/chapter.sgml [doc-jp 8399]
(new) -> 1.4 colophon.sgml

Submitted by: Shun SUZUKI <si006@ccm.gs.niigata-u.ac.jp>