docs(prlint): fix wrong path in sample commands (#31295)

### Reason for this change



In the sample commands:

```console
cd tools/prlint
yarn install
```

But the correct path is `tools/@aws-cdk/prlint`.

### Description of changes



Fix the path.

### Description of how you validated changes



### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

tools/@aws-cdk/prlint/README.md

@@ -48,7 +48,7 @@ to the PR.
 # Installation
 
 ```console
-cd tools/prlint
+cd tools/@aws-cdk/prlint
 yarn install
 ```