First, Merry Christmas to all!
These days I finally had some time to sit and type this document which was long overdue. It is not a full MMBasic manual (those have already been written by its author), but focuses more on the additions on ELLO from user's perspective. I will keep updating this document when I can with the hope that one day it will become a full book for ELLO. If anyone else is interested in helping as well, please let me know.
The file is now in the project's GitHub repository: https://github.com/knivd/ELLO-2M