Clean up README and CONTRIBUTING guide

[spectranaut]

Now that the ARIA working group owns this document.

[ZoeBijl]

What would this involve?

[spectranaut]

I think making the Contributing guide not mention the Web Application Working Group, and maybe the readme should say something about this document being controlled by the ARIA working group and reference the ARIA readme?

This makes me realize I don't think we triage new issues in this repository in the ARIA working group atm... @jnurthen can you fix that?

[ZoeBijl]

I’ve made a draft PR at #537; can you verify the staff contact is indeed Daniel Montalvo?

[jnurthen]

I think making the Contributing guide not mention the Web Application Working Group, and maybe the readme should say something about this document being controlled by the ARIA working group and reference the ARIA readme?

This makes me realize I don't think we triage new issues in this repository in the ARIA working group atm... @jnurthen can you fix that?

I can if we want to - Scott normally does a good job triaging without involving the whole group though. Do we want that to change?

[scottaohara]

personally, i'm fine with this not being included in the triage. If I need help / want to discuss something with the group, I'd be happy to bring those up on a case by case basis.