content: API reference for NavController provider

_Original issue by @PeterHdd on [2019-02-28T13:19:24Z](https://github.com/ionic-team/ionic/issues/17639)_

# Documentation

I imported the following:

`import { NavController } from '@ionic/angular';`

and when checking the methods I found that it contains: `navigateBack`, `navigateRoot`, and `navigateForward`.. but I can't find these methods in the documentation.

In the `ion-nav` api: https://ionicframework.com/docs/api/nav I found different methods, not sure if this is a different class other than `navcontroller`. I would appreciate if someone can just clear this to me.

Thank you!