For a technical, in-depth overview of IncludeOS and how it was made I find the main authors presentation at Cppcon 2017 is a pretty good introduction:

https://www.youtube.com/watch?v=h7D88U-5pKc (one hour, quite entertaining).

There is also the original paper which was presented at the 2015 IEEE 7th International Conference on Cloud Computing Technology and Science (CloudCom).

https://ieeexplore.ieee.org/abstract/document/7396164