I used Ivan Sanchez's Leaflet.ImageOverlay.Rotated.js plugin for a project at work, so I threw some of the enhancements I made into a not-so-pretty UI in case someone else wanted to use them.
I added a function that allows you to drag and drop the image overlay, which is much easier than having to resize it in order to move it. I also added some basic displays for the marker coordinates, and an opacity slider for a better UX. We are saving this information to the database, so I made a simple "export" button in case you wanted to POST your data for your georectified image to the server.
The original project can be found here: https://github.com/IvanSanchez/Leaflet.ImageOverlay.Rotated