s element mapping update

[scottaohara]

HTML AAM has been updated to map the s element to role=deletion with Chromium and Gecko having implemented this change, and an issue against webkit has been filed for them to do so as well.

ARIA in HTML is being updated w3c/html-aria#466 to reflect this change

Previously any role was allowed for the s element. That is still true but for the fact that like other elements with implicit roles it is now 'not recommended' for devs to use role=deletion on the element since it will already expose that.

The checker can surface this as an unnecessary role, as it does for other elements where their role is redundantly added.

[gezlemon]

Thanks, @scottaohara Updated to map the s element to role=deletion.

[scottaohara]

thank you @gezlemon