Add value prop for convenience

[zqianem]

Is a numeric value instead of a one-element array.

This is a bit of hack, admittedly. Addresses #12. Not sure how you wanted to update the docs for this.

[simeydotme]

oh hey @zqianem !

This is kind of what I had running originally as a workaround (as I described in #12) but I was unable to achieve what you have here (I didn't think about two-way binding the values to each other)... I haven't had time to check it out and play with it yet but I can see the logic and it seems sound. I just worry about recursion or looping, or passing both props simultaneously.

I'll get around to testing it thoroughly and determine the impact it has in due course... but for now thanks a lot for the contribution !! 🙇