docs: remove dead link from README.md

[siavashyj]

Remove reference to the deleted /benches directory.

ref:

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #121 will not alter performance

_{Comparing siavashyj:patch-1 (6e3ada2) with main (6c0a187)}

Summary

✅ 73 untouched benchmarks

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:loudspeaker: Thoughts on this report? Let us know!

[siavashyj]

Any idea on why the check is failing?

[sydney-runkle]

Looks like samuel fixed this already, but thanks for the PR!