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/rgbled.py

@@ -0,0 +1,28 @@
+from gpiozero import RGBLED
+from time import sleep
+
+led = RGBLED(red=9, green=10, blue=11)
+
+led.red = 1  # full red
+sleep(1)
+led.red = 0.5  # half red
+sleep(1)
+
+led.color = (0, 1, 0)  # full green
+sleep(1)
+led.color = (1, 0, 1)  # magenta
+sleep(1)
+led.color = (1, 1, 0)  # yellow
+sleep(1)
+led.color = (0, 1, 1)  # cyan
+sleep(1)
+led.color = (1, 1, 1)  # white
+sleep(1)
+
+led.color = (0, 0, 0)  # off
+sleep(1)
+
+# slowly increase intensity of blue
+for n in range(100):
+    led.blue = n/100
+    sleep(0.1)