docs: fix code block language in redirecting docs (#72944)
## Summary
Update incorrect code block languages at [redirecting
document](https://github.com/vercel/next.js/blob/canary/docs/01-app/02-building-your-application/01-routing/07-redirecting.mdx).
### Improving Documentation
- [x] Run `pnpm prettier-fix` to fix formatting issues before opening
the PR.
- [x] Read the Docs Contribution Guide to ensure your contribution
follows the docs guidelines:
https://nextjs.org/docs/community/contribution-guide
Co-authored-by: Delba de Oliveira <32464864+delbaoliveira@users.noreply.github.com>
