[web-annotation] Issue: 'generated' and 'modified' date/time properties specific reference and format marked as i18n-review

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

== 'generated' and 'modified' date/time properties specific reference 
and format ==
[raised by Addison Phillips, not yet discussed by i18n WG]

The generated and modified properties store the creation and 
most-recent modification timestamps for an annotation. The spec 
requires ("MUST") date times follow a very old WG note 
[http://www.w3.org/TR/NOTE-datetime] that defines a profile of 
ISO8601, but does not specify a specific format within that note. It 
goes on to recommend ("SHOULD") `xsd:dateTime` "with a timezone" 
(which is a specific format that happens to be one of those enumerated
 in the WG note). Generally, when working with time values, the 
minimal acceptable value would be a `full-date` (and having a 
timestamp, i.e. `date-time` is preferable). `RFC3339 `defines these 
specific keywords and would be my suggestion as a better replacement 
for the WG note. XML Schema and `xsd:dateTime` is also a valid 
reference to use here.


See https://github.com/w3c/web-annotation/issues/217