Complete Precis Ontology documentation

[rukmal]

Need to add the following sections (check WiDocO documentation for more on how to actually do this):

• Introduction
• (maybe new) abstract
• Overview
• Description
• References (probably empty for the Precis ontology; not the toolkit)
• WiDocO configuration file
• Icon and UML diagram for the ontology

Also consider adding documentation build to the makefile to simplify things further.

[rukmal]

Remember to include renaming index-en.html to index.html if you put this in the Makefile

[rukmal]

I do not remember how to use WiDiCo, or where the original config is.