Consume a11ysupport package

[Ryuno-Ki]

Over in mdn/content#7445 we pondered the possibility to consume https://www.npmjs.com/package/a11ysupport to help us maintain ARIA / AT pages on MDN.

I've contacted the author in accessibilitysupported/a11ysupport.io#179 and he's open to the idea.

I haven't looked into what's needed exactly, but want to fill an issue, so I don't forget about it here.

Also, be aware, that the package itself might get be superseded by a W3C Community Group effort. Eric is keeping us in the loop if he learns more about it.

[Malvoz]

Excuse my ignorance, I thought all support data on MDN came from https://github.com/mdn/browser-compat-data/. There's a related issue: mdn/browser-compat-data#6553, if that's relevant somehow. 😋

[caugner]

I will move this over to discussions.