Fix a link.

[kkshinkai]

Current link is 404

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon.

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[kkshinkai]

r? @steveklabnik

[jonas-schievink]

Thanks! This link is already being fixed by #73985 though, so closing in favor of that.