[tei-council] non-deterministic content models

[Syd Bauman]

I've elaborated the section on the wiki.

> In our discussion of giving up DTDs, did someone say that if we
> gave up XSD as well, we could have non-deterministic content
> models? And then Lou said that there might be value in keeping to
> deterministic content models if only to clarify our thinking.
> 
> If so, I'd like to elaborate
> 
> http://wiki.tei-c.org/index.php/TEI-Council-FAQ#What_is_a_non-deterministic_content_model.3F
> 
> to explain that only a certain type of validation fails.