Add note on use of ARIA to uniquely identify nav elements

[schalkneethling]

In the documentation linked to below, a common usage pattern of the nav element is discussed. There is however no mention of using either aria-label or aria-labelledby to convey the purpose of each navigational aid and also distinguish them from each other.

While there is a link provided to ARIA in HTML for authors[1] this also does not mention this pattern. Adding an entire section to the HTML docs around this might not be appropriate but, perhaps a short mention and a link to the ARIA landmark docs[2] is possible?

Something like:

Accessibility note: It is a common design pattern to uniquely label each nav element when there is more than one on a page. Read more

1 - nav element ARIA in HTML entry
2 - Navigation landmark docs

Linked Docs Section

https://html.spec.whatwg.org/commit-snapshots/31b264a56253e7b047d1cc6a02a4c6337dd6cff5/#the-nav-element

In the following example, there are two nav elements, one for primary navigation around the site, and one for secondary navigation around the page itself.