examples: add a clean-examples target, to clean all of the examples.
examples: add a clean-examples target, to clean all of the examples.

SuperHouse/esp-open-rtos,bhuvanchandra/esp-open-rtos,ourairquality/esp-open-rtos,bhuvanchandra/esp-open-rtos,urx/esp-open-rtos,SuperHouse/esp-open-rtos,SuperHouse/esp-open-rtos,urx/esp-open-rtos,ourairquality/esp-open-rtos,urx/esp-open-rtos,ourairquality/esp-open-rtos,urx/esp-open-rtos,bhuvanchandra/esp-open-rtos,SuperHouse/esp-open-rtos,SuperHouse/esp-open-rtos,ourairquality/esp-open-rtos,ourairquality/esp-open-rtos,ourairquality/esp-open-rtos,bhuvanchandra/esp-open-rtos,urx/esp-open-rtos,SuperHouse/esp-open-rtos,urx/esp-open-rtos