Remove ARIA labels from containers

[andrewhick]

What’s changed

This PR removes unnecessary ARIA labels from the menu container and the main content window.

These aria-labels are used incorrectly as they are applied to <div> elements with no role. This is not permitted under the ARIA specification as a <div> has a role of generic. They are also unnecessary as:

• the <nav> element already has an appropriate label
• the main content is within a main landmark and so an aria-label is unnecessary for its container. We could move the aria-label to <main> instead but while permitted, my understanding is that it would be unnecessary.

I've tested it locally using VoiceOver and:

• the side navigation is correctly noted as "Table of contents"
• the main landmark is correctly identified as main

I believe this fixes #404 .

Identifying a user need

This came out of testing by Shabana Ali in the WCAG Primer working group, who identified the incorrect ARIA usage. We believe fails Web Content Accessibility Guidelines (4.1.2 Name, Role, Value - level A)

[tombye]

Thanks for this Andrew. It is odd these <div>s having labels but no role and that's reflected in the experience using a screen reader. This makes it better and, actually, doesn't lose any semantics because the table of contents is already wrapped in a <nav> and the content a <main>, both of which do a good job of describing what each contain.

Nice work, only adds value 👍🏻