Ensure deprecated content is properly called out

[scottaohara]

aria-grabbed and aria-dropeffect were deprecated in ARIA 1.1.
role=directory will be deprecated in ARIA 1.2.

role=directory SHOULD NOT be allowed on any element that used to allow it.
The deprecated attributes should be noted as deprecated and it should be called out that they SHOULD NOT be used by authors.

[scottaohara]

a section should be added to the specification to note that aria roles and attributes that have been deprecated should receive warnings in conformance checkers.

edit:
specifically deprecated features that have clear replacements need to be called out as author errors. deprecated features that presently have no suitable alternative, or require a long tail legacy support should receive warnings and urging to migrate to new standards, if available