how to integrate jquery select2 plugin as dropdown in AEM forms as custom apperance field, but cannot find any document or complete working example

How to integrate with the data binding? Seems Adobe AEM and Forms site has no many spelling errors causing almost 90% of the example code on the web site is not working by default, is this on purpose?

Look at this example, 

Create custom appearances for adaptive form fields | Adobe Experience Manager

There's no code to download and runnable.