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/reaction_game.py

@@ -0,0 +1,22 @@
+from gpiozero import Button, LED
+from time import sleep
+import random
+
+led = LED(17)
+
+player_1 = Button(2)
+player_2 = Button(3)
+
+time = random.uniform(5, 10)
+sleep(time)
+led.on()
+
+while True:
+    if player_1.is_pressed:
+        print("Player 1 wins!")
+        break
+    if player_2.is_pressed:
+        print("Player 2 wins!")
+        break
+
+led.off()