Fix incorrect parameter and typos in example code.
Fix incorrect parameter and typos in example code.

I had followed the example code and couldn't work out why the size rule wasn't working. It turns out there is no `max` option, instead it should be `size`.

Maybe there should also be some kind of warning issued when an invalid option is supplied. The silent failure made it difficult to debug.
siriusphp/upload,bkzhn/upload