Hi,

Here's another idea, a new dev-doc category (though I suppose we could
try to find a better name), dedicated to:

  Tools to generate, convert, view and process documentation.

This is notably meant to move software out of app-doc/ which is
specifically dedicated to "documentation collections".  Candidates:

app-doc/NaturalDocs
app-doc/doxygen
app-doc/halibut
app-doc/psmark
app-doc/xmltoman
app-doc/zeal
app-text/mandoc
app-text/texi2html
app-text/xchm
app-text/xml2rfc
app-text/xmlto
dev-util/gi-docgen
dev-util/gtk-doc
dev-util/source-highlight
sys-apps/man-db
sys-apps/texinfo

-- 
Best regards,
Michał Górny