Add in Demo/Guide in main README showcasing how to dynamically add in new CellProvider

[10000TB]

Often times in real app, there are async requests return after viewDidLoad, and we want to update UI upon that return. In this particular context of Flix, main README does not document how to dynamically add in new cellProvider, but it seems there are ways to achieve that with Flix. So it would be nice to add a new section for that.

@DianQK Wdyt ?

[DianQK]

Just call build, but you can hide this provider's values.

[10000TB]

build works.

But I notice that when I am call build second time, there is a short period of view freezing (in a sense where you cannot scroll, and re-build process also brings in some unwanted animation

[DianQK]

try this code:

tableView.flix.animatable.build(providers).decideViewTransition = { changesetInfos in
    // ...
    return ViewTransition.reload
}

[10000TB]

Huge thanks @DianQK !