[web-annotation] Issue: Remove "and so forth", clarify utf-8 encoding marked as editor_action

azaroth42 has just labeled an issue for 
https://github.com/w3c/web-annotation as "editor_action":

== Remove "and so forth", clarify utf-8 encoding ==

Extracted from #227 discussion, we should remove the phrase "and so 
forth" from the text normalization description to ensure that 
implementations do not go on and perform arbitrary and 
non-interoperable content normalization.

We should clarify that the recommendation for encoding in UTF-8 is a 
requirement from JSON for recording the information, rather than part 
of the normalization routine.  This is important as 
TextPositionSelector inherits the normalization description, and it 
MUST NOT encoding in UTF-8 before counting. 

See https://github.com/w3c/web-annotation/issues/237