Auto merge of #10216 - chansuke:hotfix/fix-spelling, r=llogiq

Auto merge of #10216 - chansuke:hotfix/fix-spelling, r=llogiq

Fix spelling inconsistence of `mdBook`

I was reading both [mdBook Documentation](https://rust-lang.github.io/mdBook/) and  [The Clippy Book](https://doc.rust-lang.org/nightly/clippy/development/infrastructure/book.html#the-clippy-book) and felt that it's easier to read to unify the notation of `mdBook`.

- \[ ] Followed [lint naming conventions][lint_naming]
- \[ ] Added passing UI tests (including committed `.stderr` file)
- \[x] `cargo test` passes locally
- \[ ] Executed `cargo dev update_lints`
- \[ ] Added lint documentation
- \[x] Run `cargo dev fmt`

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changelog: none