rustdoc: Improve accessibility of rustdoc pages

[mitaa]

fixes#33131

r? @alexcrichton

[durka]

Can we test this? Is there some tool that pulls out elements in the same order that screen readers do, and we can check the order?

[mitaa]

preview is available here

@durka
Not sure, I've tested this using ChromeVox which exhibited the same behaviour as described in the referenced issue.

cc @camlorn

[alexcrichton]

@bors: r+ bb9ec82

[ahicks92]

This appears to do it for Firefox and NVDA, my combination.

It's not testable though, no. Not as far as I know. In my experience, 99% of the time it's DOM order. But I'm not confident enough on that to say 100% of the time because there's at least 12 combinations just for Windows now and I'm only on one of them. Screen readers and accessibility and the like are the least specified and least implemented web technologies, and even basic stuff essentially requires testing all of the combinations that you care about.

Thanks for the quick turnaround. This improves usability a lot. Usually I report stuff and it's just like "We'll do it sometime", where actually they mean never. I hate that I can only report for something like this.