How the Ontology documentation works:

A script generates references for all ontologies. Each ontology entity has
an id which matches its abbreviated URI (Example: nao:prefLabel). Thus, in
order to link to any ontology entity (property or class) just use the xref
or the link tag with the appropriate linkend (link allows to specify a 
custom text which xref uses the title from the linked element).

Author information goes into the <onto>-authors.docbook file.

All other documentation goes into the <onto>-main.docbook file which should
contain sections and optional appendixes.
Please use <onto>:sec-<topic> as the id for a section.

Each ontology gets its own chapter which has as an id the namespace abbreviation
(Example: <chapter id="nfo">).