Update Jest config with SWC docs (#37705)
Update Jest config with SWC docs (#37705)

## Motivation/ Context
- When upgrading `next` from `11` to `12`, I followed [Upgrade guide from 11 => 12](https://nextjs.org/docs/upgrading#upgrading-from-11-to-12). I removed `.babelrc` to opt-in `SWC`. I thought that's all, but after removing `.babelrc`, Jest broke immediately. So I follow the guide https://nextjs.org/docs/advanced-features/compiler#jest to configure Jest to work with SWC. I copied the content of `jest.config.js` to my project but it does not work. The reason:
```diff
-const createJestConfig = nextJest({ dir }) // `dir` IS NOT DEFINED
+const createJestConfig = nextJest({ dir: './' }) // Should change to this. Sync with https://nextjs.org/docs/testing#setting-up-jest-with-the-rust-compiler
```
- This PR is to help others to configure Jest with SWC by copying code from the documentation site without encountering the same issue as I did.

## Documentation
- [x] Update the docs so users can just copy and paste when configuring Jest with SWC (Sync with https://nextjs.org/docs/testing#setting-up-jest-with-the-rust-compiler)
- [x] Make sure the linting passes by running `pnpm lint`
- [x] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)

## Future work
- Since [Upgrade guide from 11 => 12](https://nextjs.org/docs/upgrading#upgrading-from-11-to-12) did not mention anything about Jest. If I remove `.babelrc` to opt-in SWC. The current Jest settings will crash (since it's using babel). We likely want to update the Upgrade guide to mention this cc: @leerob 
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