Add a new translation and connect it to the build:

(new) -> 1.20 books/handbook/preface/preface.sgml

Submitted by: Hiroo Ono <hiroo at oikumene dot gcd dot org>
Reviewed by: Arasaki <arasaki at fiberbit dot net>
References: [doc-jp-work 1044, 1090, 1096, 1097, 1119]