Input Purposes section with HTML autocomplete values

I've set up a branch to change the Input Purposes section to use the 
values exactly from HTML autocomplete, as discussed in today's 
teleconference:

https://rawgit.com/w3c/wcag21/common-purposes-autocomplete/guidelines/#input-purposes

I will propose this to the Director as a solution to the question he 
raised about that section, which was that it was unclear if the list as 
previously shown was a merely editorial change from the Candidate 
Recommendation. I will merge the branch if he approves. Meanwhile, if 
anybody would like to comment on this before I discuss this with Ralph 
and Philippe tomorrow, please do.

Michael