Convert recipe examples to includes

Makes it much easier to test things - no copying'n'pasting just run the
examples straight from the dir (after wiring stuff up)

docs/examples/all_on_1.py

@@ -0,0 +1,9 @@
+from gpiozero import FishDish
+from signal import pause
+
+fish = FishDish()
+
+fish.button.when_pressed = fish.on
+fish.button.when_released = fish.off
+
+pause()