Packages without a file and/or link
/usr/share/gnome/help/<package>/C/index.html have documentation not
accesible in "Gnome Help Browser" even if such help is available. Such
packages currently include at least gnumeric, gnomecal and rp3; maybe
more. Even if quite extensive docs for gnumeric actually do exist users
are not likely find them thus making the whole thing rather ineffective.
gnomecal is at least reachable through Gnome User Guide but gnumeric
Adding a missing link "by hand" automagically creates a corresponding
entry in ToC of Gnome Help.