Corrected code block hyperlink (#9602)
## Summary
Apparently MkDocs doesn't like when reference-style links have
formatting inside :)
<details>
<summary>Screenshots (before and after the change)</summary>
<img width="1235" alt="61353"
src="https://github.com/astral-sh/ruff/assets/77130613/e32a82bd-0c5d-4edb-998f-b53659a6c54d">
<img width="1237" alt="15526"
src="https://github.com/astral-sh/ruff/assets/77130613/bdafcda5-eb9c-4af6-af03-b4849c1e5c81">
</details>
