Fix typo in cargo-bench.md

[michaelkirk]

No description provided.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @weihanglo (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

• @rustbot author: the review is finished, PR author should check the comments and take action accordingly
• @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

[weihanglo]

Thanks for the contribution.

The build failed. See https://github.com/rust-lang/cargo/actions/runs/9046252088/job/24856873540?pr=13903#step:6:215:

Detected changes of man pages:
 M src/doc/src/commands/cargo-bench.md

Please run `cargo build-man` to rebuild the man pages
and commit the changes.