[Accessibility] Add roles and missing attributes on the markup

[magsout]

I think in the first time we can add the roles (banner, aside, etc ..) and basic attributes of the elements, we have forgotten (like type = "button")(such as type = "button")

[karlcow]

Thanks @magsout for starting this. 🏆

Rephrased a bit the title. If it's too wide. I would encourage to reduce the scope. And create more issues for things to fix. :) It will hopefully help to attract someone who's willing to do a first-patch :)

[andrewmcgivery]

Taking a look at this. Probably going to need a few pull requests for this. Bunch of small issues. :)

[andrewmcgivery]

See pull request: #363

[miketaylr]

Awesome!

[andrewmcgivery]

This can probably be closed now.

[karlcow]

according to @andrewmcgivery, let's close