HTML-AAM: determine best UIA mapping for <kbd>

[jasonkiss]

From @cyns on January 12, 2016 21:48

kbd could be mapped as either

1. a new text attribute
2. a group with localized control type (maybe "user input"?)

Copied from original issue: w3c/aria#170

[boggydigital]

Longer term this should be ControlType: Text and LocalizedControlType: "user input"