Updated techniques for SC 2.4.6

I updated the techniques for SC 2.4.6 to reflect the comments from the
survey. 
http://trace.wisc.edu/wcag_wiki/index.php?title=How_to_Meet_Success_Crit
erion_2.4.6

There were several issues that I wanted to check with the team:

*	Yvette suggests adding a failure ""Missing labels by using one
label for multiple input fields" since many forms use one label (Name)
for two input boxes (or three in the case of Dutch names with prefixes
like "van der").
*	Should the descriptive heading technique require adhering to
hierarchy? Should there be an advisory technique that heading levels
adhere to hierarchy?
*	Makoto wants the titles of delivery units to be unique. I don't
see how we can require that, unless we have some way to defining the set
in which they should be unique
*	Sofia wants example 1 of the descriptive title technique to put
the most specific information first. We can easily change the example
description, but then we can't use WGBH as an example.

Loretta Guarino Reid
lguarino@adobe.com
Adobe Systems, Acrobat Engineering