Made it clear sample won't run on AVR Arduinos
Made it clear sample won't run on AVR Arduinos

Ref: https://github.com/Azure/azure-iot-sdks/issues/343

I think i've been a bit too harsh in the issue comments, sorry about that, you did actually list the prereqs correctly but having an ATWINC1500 breakout myself i disregarded the fact that a 32-bit ARM Cortex M0 is a must to run. This PR makes things crystal clear.
kevinledinh/azure-iot-sdks,emirotin/resin-azure-iot-sample,Eclo/azure-iot-sdks,kevinledinh/azure-iot-sdks,Eclo/azure-iot-sdks,damonbarry/azure-iot-sdks-1,emirotin/resin-azure-iot-sample,Eclo/azure-iot-sdks,damonbarry/azure-iot-sdks-1,damonbarry/azure-iot-sdks-1,kevinledinh/azure-iot-sdks,emirotin/resin-azure-iot-sample,oriolpinol/azure-iot-sdks,Eclo/azure-iot-sdks,dominicbetts/azure-iot-sdks,damonbarry/azure-iot-sdks-1,oriolpinol/azure-iot-sdks,oriolpinol/azure-iot-sdks,oriolpinol/azure-iot-sdks,Eclo/azure-iot-sdks,emirotin/resin-azure-iot-sample,damonbarry/azure-iot-sdks-1,Eclo/azure-iot-sdks,kevinledinh/azure-iot-sdks,damonbarry/azure-iot-sdks-1,kevinledinh/azure-iot-sdks,damonbarry/azure-iot-sdks-1,oriolpinol/azure-iot-sdks,Eclo/azure-iot-sdks,oriolpinol/azure-iot-sdks,dominicbetts/azure-iot-sdks,Eclo/azure-iot-sdks,emirotin/resin-azure-iot-sample,dominicbetts/azure-iot-sdks,emirotin/resin-azure-iot-sample,kevinledinh/azure-iot-sdks,dominicbetts/azure-iot-sdks,dominicbetts/azure-iot-sdks,kevinledinh/azure-iot-sdks,dominicbetts/azure-iot-sdks,dominicbetts/azure-iot-sdks,kevinledinh/azure-iot-sdks,emirotin/resin-azure-iot-sample,oriolpinol/azure-iot-sdks,damonbarry/azure-iot-sdks-1,dominicbetts/azure-iot-sdks,oriolpinol/azure-iot-sdks,kevinledinh/azure-iot-sdks,Eclo/azure-iot-sdks