The package is unlikely to see any upstream activities and doesn't have any open bug reports. It requires little attention.
The package description is: DocBook: The Definitive Guide - HTML version
The official reference manual for the DocBook 4.x SGML and XML DTD,
by Norman Walsh, Leonard Muellner, and Bob Stayton. This version is
an evolution of the book of the same name published by O'Reilly
(which documented DocBook 3.1).
This is a work in progress, which attempts to fully document DocBook
4.5, but may be inconsistent in some places.