Breadcrumbs: restore Aria attribute and link

[chalin]

This reverts the changes to the breadcrumb partial done in #1011. In particular, this PR:

• Reinstates the aria-current attribute
• Reinstates the last breadcrumb as a link

In #1011, @at055612 notes that:

Making the leaf item not a link is possibly contentious but a quick google suggests this is an accepted practice. I think having a link to the page you are on is confusing and offers no value.

I agree on both points, and ( propose the following (which feels like a win-win): ensure that all breadcrumbs are links, but effectively disable the last breadcrumb. I use Bootstrap's disabled class and the Aria aria-disabled attribute. The documentation for aria-disabled explicitly mentions as a use case the situation of a link/button to a self.

Visually, you'll see no difference, e.g.:

Preview: for example see https://deploy-preview-1068--docsydocs.netlify.app/docs/get-started/docsy-as-module/

Note that while the last breadcrumb is disabled, its link can still be visited.

[LisaFC]

LGTM!

[at055612]

@chalin May be a bit late as this has already been merged, but does it make sense to have aria-current="page" for the leaf item on each of the the taxonomy results page cards (https://deploy-preview-1068--docsydocs.netlify.app/tags/labelling/).

Agree with the use of aria-disabled and disabled links, thanks for fixing that.

[chalin]

As I mentioned elsewhere, I think that all ARIA attributes should be removed in that case. Let's move this discussion to #1071.