Added CAN-over-Ethernet interface

[gbeine]

Sirs and Sirens,

thanks a lot for the python-can library.

I'd like to add a link to my CoE (CAN over Ethernet) bus interface to the docs.
The interface plugin location is here: https://c0d3.sh/smarthome/python-can-coe/

Maybe, it can be added to this list: https://python-can.readthedocs.io/en/stable/plugin-interface.html

Thanks again and keep on hacking!