[web-annotation] Issue: Processing language for mono-lingual and internationalized resources marked as i18n-review

r12a has just labeled an issue for 
https://github.com/w3c/web-annotation as "i18n-review":

== Processing language for mono-lingual and internationalized 
resources ==
The main conclusion of #335 and #337, which is partly implied in the 
definition of the processingLanguage is that the processingLanguage is
 not needed for mono-lingual and for internationalized resources, and 
this should be derived from the dc:language.

The concrete proposal is to add a non normative note indicating that:
"For internationalized resources and mono-lingual resources used in 
body or target, the dc:language should be provided, and no processing 
language should be set"

See https://github.com/w3c/web-annotation/issues/342