There is no need for documentation. They just give you an HTML5 input type=”number” which as a step, min, and max attributes with they provide access to. This is not something custom that ACF has added to their system. You can read more about it below.
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/number
If you are looking to create custom filtration you will have to look at some type of validation script whether it be html5 validation or a jQuery library.
