docs(create-next-app): add --use-npm (#24018)
docs(create-next-app): add --use-npm (#24018)

Document `--use-npm`.

## 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

- [x] Make sure the linting passes

zeit/next.js,azukaru/next.js,azukaru/next.js,flybayer/next.js,azukaru/next.js,azukaru/next.js,JeromeFitz/next.js,zeit/next.js,JeromeFitz/next.js,flybayer/next.js,flybayer/next.js,JeromeFitz/next.js,JeromeFitz/next.js,zeit/next.js,flybayer/next.js