Add a note about the auto-created empty directory (#43219)

It isn't clear whether the `create` step needs to be run inside an empty directory (avoiding conflicts with existing content in the current working directory), or whether it can be run in a directory with existing contents, and its output would be placed in an empty directory automatically created from the project name.



## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`

## 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.
- [ ] Errors have a helpful link attached, see `contributing.md`

## Documentation / Examples

- [x] Make sure the linting passes by running `pnpm build && pnpm lint`
- [x] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

docs/getting-started.md

@@ -19,7 +19,7 @@ If you have questions about anything related to Next.js, you're always welcome t
 
 ## Automatic Setup
 
-We recommend creating a new Next.js app using `create-next-app`, which sets up everything automatically for you. To create a project, run:
+We recommend creating a new Next.js app using `create-next-app`, which sets up everything automatically for you. (You don't need to create an empty directory. `create-next-app` will make one for you.) To create a project, run:
 
 ```bash
 npx create-next-app@latest