Tutorials need to specify `rimraf` dependance?

### Describe the Bug

On using the tutorial #57 as a start, using `npm run build` yields an error. Just need to add a note to run `npm install` in the docs first
```
> rust-webpack-template@0.1.0 build ........
> rimraf dist pkg && webpack

sh: 1: rimraf: not found
```

### Expected Behavior

Default templates should compile :pray: 
