It’s now possible to build the material in doc, including the handbook, using tools from pkgsrc, thanks to work from both me and Victor Balada Diaz.  (The doc framework was previously ports-centric.)  If you’re curious, the needed packages appear to be netbsd-doc, libxslt, docbook-xsl, ghostscript-gnu, netpbm, and jade, along with tex-jadetex if you want to prodcue it in PDF form.