Why does Microsoft say FlexLayout is a child of ScrollView?

I've read in https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/layouts/flex-layout

Notice that the FlexLayout is a child of a ScrollView. If there are too many rows to fit on the page,
then the ScrollView has a default Orientation property of Vertical and allows vertical scrolling.

But in https://docs.microsoft.com/en-us/dotnet/api/xamarin.forms.flexlayout?view=xamarin-forms it is written:

public class FlexLayout : Xamarin.Forms.Layout<Xamarin.Forms.View>

and in https://docs.microsoft.com/en-us/dotnet/api/xamarin.forms.scrollview?view=xamarin-forms

public class ScrollView : Xamarin.Forms.Layout

I don't see here that FlexLayout is a child of a ScrollView.
(and sorry..when I need to scroll, using a FlexLayout will not be enough).
Do I miss something?