gnome-doc-utils

gnome-doc-utils is a collection of documentation utilities for the
project.  Notably, it contains utilities for building documentation
and all auxiliary files in your source tree, and it contains the
DocBook XSLT stylesheets that were once distributed with Yelp.
Starting with Gnome 2.8, Yelp will require gnome-doc-utils for the
XSLT.

Website: http://ftp.gnome.org/pub/GNOME/sources/gnome-doc-utils/
