docs: fix code block language in error pages (#72943)
## Summary
Update code block language in [error
pages](https://github.com/vercel/next.js/tree/canary/errors).
### 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>
