"$scope.viewModel(this)" is not documented

Step 3.3 at [1] uses following code which doesn't seem to be explained or documented anywhere:

```
$scope.viewModel(this);
```

There is also a related StackOverflow question[2] which no-one has been able to answer yet.

[1] https://www.meteor.com/tutorials/angular/collections
[2] http://stackoverflow.com/questions/37831978/difference-between-reactivethis-attachscope-and-scope-viewmodelthis

Start with Step 3.3 of the Meteor Angular collections tutorial and inspect the unexplained `$scope.viewModel(this);` example. Compare the related StackOverflow question to establish what needs explaining; done means the tutorial or project documentation clearly describes this call and its relationship to the surrounding Angular Meteor code.

Written by the indexing model from the issue text.