And some small editing changes.

Comment From: philwebb

We should double check the condition works because I'm not sure if the new backend sets the same property name.

Comment From: wilkinsona

@Buzzardo For future reference, we try to keep individual commits focussed on a single change. This PR's mixing improvements to the links to the other forms of the documentation with some general editing of the multi-page documentation's index. I'll split things up while merging this and have happened https://github.com/spring-projects/spring-boot/issues/27805 to track the editorial changes.

Comment From: wilkinsona

We should double check the condition works because I'm not sure if the new backend sets the same property name.

Good catch, Phil. As proposed, the changes remove the sentence beginning "This document is also available as …" from both the single-page documentation and from the PDF.

Comment From: wilkinsona

Thanks, @Buzzardo. I've merged these changes into main.

For future reference, it'd be greatly appreciated if you could build your changes (./gradlew spring-boot-project:spring-boot-docs:build should do the trick) before submitting them and double-check that they're rendered as expected.