Merge pull request #77 from RaspberryPiFoundation/dev

uds docs fix

Author: Martin O'Hanlon

docs/examples/ultrasonic_distance_sensor.py

@@ -1,7 +1,7 @@
 from picozero import DistanceSensor
 from time import sleep
 
-ds = DistanceSensor(echo=4, trigger=5)
+ds = DistanceSensor(echo=2, trigger=3)
 
 while True:
     print(ds.distance)