Firm up the documentation for icons

According to https://developer.apple.com/library/content/qa/qa1686/_index.html the icon doc page at http://cordova.apache.org/docs/en/5.1.1/config_ref/images.html lacks the 87x87 icon (Icon-Small@3x.png) and a few others for iOS and also the naming is not 100% compatible. Any reason to not use the exact same names?

I know you are not responsible for the same PhoneGap documentation, that is in complete disarray, but you might poke them to update their information.