Add explicit heading aria-level to complement heading role

[bollwyvl]

References

• fixes Get CI audits back to passing #455

Code Changes

• ensures that any starttag which includes a ROLE will also get the (implicit) fallback aria-level of 2

[bollwyvl]

Ah, in the remaining failing case, it's not firing on the toc that's included directly in the content. Looks like doing it at the docutils level will be required.

[bollwyvl]

This may be a case where lighthouse is wrong, as the guidance suggests the implicit value is fine (even though it's required), but this gets us back to all green, even if I don't love it. As the docutils nodes aren't perfectly aligned with the semantic level of the document, I don't think we could get to a "right" number for both sidebars and in-content toctrees, much less any other captions we'd see.

[choldgraf]

This LGTM - it's not too complex and it makes things slightly better, so I am +1 :-)