Update step_03.ngdoc

Hello,

when I run protactor, I got this error message:
```
Failures:
1) PhoneCat App Phone list view should display the current filter value in the title bar
Message: ReferenceError: query is not defined
Stacktrace: ReferenceError: query is not defined
```

It's because query is not retrieved from model. So I added it.

Hope this helps