This pull request add typescript to the current redux-toolkit example on next.js. @markerikson suggested this nice idea to add a ts example: https://twitter.com/acemarke/status/1370877104527712259?s=20
This example is with the previous redux-toolkit example which was more complex. An example with the current example is available here: https://github.com/vercel/next.js/pull/23249
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
## Documentation / Examples
- [ ] Make sure the linting passes