Add example full integration documentation

There is a documentation describing how to set up a full example found in the OpenPAYGO HW repository here: https://github.com/EnAccess/OpenPAYGO-HW/blob/main/examples/arduino_implementation/documentation/How%20to%20make%20an%20appliance%20Pay%20as%20You%20Go.pdf

It would be great if we can have this example in the `OpenPAYGO-docs` as MD rather than PDF.