Add a MapImage to a MapImageLayer

[JamesWiggins]

In the documentation for MapImage, you state that 'The MapImage class can also be used to create a geo-referenced image file for use with the MapImageLayer.' However, this functionality doesn't exist. I would like an easy way to overlay a geo-referenced image file over the top of a map. See documentation for MapImage: MapImage API

[BjornSvensson]

As of version 4.3, the 4.x JSAPI doesn't yet support adding georeferenced images. The documentation for MapImage is incorrect (and we will update that).