Added support for header_templates in generated docs

[UebelAndre]

Changes

• Pages now render with the title of the page and not the previously hard coded Rust Rules
• Users can now optionally pass a header_template

[illicitonion]

Mechanically this seems reasonable, but I don't really know stardoc or anything about our documentation situation, so I'll leave for others to weigh in :)

[UebelAndre]

Mechanically this seems reasonable, but I don't really know stardoc or anything about our documentation situation, so I'll leave for others to weigh in :)

I'll ask David. I figured you'd be a good reviewer since you had just reviewed the crate universe docs PR. But I realize that wasn't a change to docs generation 😅

[dfreese]

Will try and take a look at this this evening.

[UebelAndre]

For a bit of extra context, I'm wanted this functionality to be able to add something like https://github.com/UebelAndre/rules_rust/blob/docs/docs/rust_analyzer.md

If we can have custom headers then we can add more contextual documentation about rules there, keep the doc attributes of each rule more focused, and avoid polluting the landing page.

[dfreese]

Sorry for the delay, family stuff took precedence.

Generally looks fine to me. One question.

[UebelAndre]

@dfreese ready for another review