Updated the /ns files

Ie, the ontology files (oa.{html,ttl,jsonld,rdf,owl}) as well as the jsonld context file (anno.{jsonld,json}).

A quick check from somebody would be good, just to be on the safe side!

(Thanks Rob for the fixes.)

Ivan

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Ivan Herman, W3C
Digital Publishing Technical Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
ORCID ID: http://orcid.org/0000-0003-0782-2704