Improve code doc

[RicardoRB]

Unfortunately, it isn't totally clear what the parameters do.

It would be great to explain it better in the code docs.

  /// Configure your app with [Momentum] root widget.
  ///
  /// The parameter `child` is not required for *unit testing*.
  factory Momentum({
    Key? key,
    Future<void> Function()? initializer,
    Widget? child,
    Widget? appLoader,
    required List<MomentumController> controllers,
    List<MomentumService>? services,
    ResetAll? onResetAll,
    bool? disabledPersistentState,
    bool? enableLogging,
    int? maxTimeTravelSteps,
    bool? lazy,
    int? minimumBootstrapTime,
    BootstrapStrategy? strategy,
    PersistSaver? persistSave,
    PersistGet? persistGet,
    String? testSessionName,
    void Function()? restartCallback,
  })