Reference Guides breadcrumb in page headers is not hyperlinked

[scottfrederick]

In the Antora-based docs, each section of the navigation breadcrumbs at the top of a page should be a hyperlink. This is not the case in the Reference Guides (for example https://docs.spring.io/spring-boot/reference/using/index.html), where the Reference Guides breadcrumb is not a link.

[scottfrederick]

Closing in favor of #40135