The use cases table, modified, for comment

To read, including all of our comments from today, with assistance from
Doug Schepers:

http://w3c.github.io/dpub-accessibility/extended-description-analysis.html#use-cases

to access the HTML in order to modify it,

https://github.com/w3c/dpub-accessibility/blob/gh-pages/extended-description-analysis.html

We will finalize this early next week, when Tzviya is available for comment.

Deborah