docs: fix code block language on forbidden (#73622)
## Summary
Change `tsx` and `jsx` to `ts` and `js` code block.
### 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
