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/traffic_lights_1.py

@@ -0,0 +1,20 @@
+from gpiozero import TrafficLights
+from time import sleep
+
+lights = TrafficLights(2, 3, 4)
+
+lights.green.on()
+
+while True:
+    sleep(10)
+    lights.green.off()
+    lights.amber.on()
+    sleep(1)
+    lights.amber.off()
+    lights.red.on()
+    sleep(10)
+    lights.amber.on()
+    sleep(1)
+    lights.green.on()
+    lights.amber.off()
+    lights.red.off()