Accessible User support: A11y Semantics

[djnugent]

Is your feature request related to a problem? Please describe.
My app serves users with disabilities. I try my best to make the app accessible as possible. Especially with screen readers.

Describe the solution you'd like
It'd be great if the generated widgets were wrapped in Semantics() to assist screen readers

Describe alternatives you've considered
I've thought about wrapping the entire markdown widget in a Semantics() but that hide the headers, links, and such.