Broken link to `Arbitrary` trait in 'Structure-Aware Fuzzing' section

[shannynalayna]

The link to the Arbitrary trait in the last sentence of the first paragraph of the Structure-Aware Fuzzing section doesn't lead to the correct crate docs for the Arbitrary crate.

It looks like the link is resolving to the correct URL, but includes a backslash that might be causing the issue I'm seeing.

The link is defined here:
[arbitrary-trait]: https://docs.rs/arbitrary/*/arbitrary/trait.Arbitrary.html

which resolves (when clicked from the book) to a "Resource does not exist" page:
https://docs.rs/arbitrary/latest/arbitrary/trait.Arbitrary.html/

The correct link is:
https://docs.rs/arbitrary/latest/arbitrary/trait.Arbitrary.html

[fitzgen]

Happy to merge a PR if you'd like to make one!