Include padding info in documentation for aesio #4493
Description
@kevinjwalters suggested adding info about padding in the aesio documentation. Some user confusion here: https://forums.adafruit.com/viewtopic.php?f=60&t=177264.
Alternatively perhaps the module might be smarter about padding itself. (I have not looked into this in any detail, so I may be wrong that it makes sense.)
BTW, nRF provides native AES support.