Update ws2812.rst

Documentation/pycardium/ws2812.rst

@@ -21,6 +21,8 @@ The ``ws2812`` module controls LEDs of the WS2812 type. Just as the ``leds`` mod
 
       import color, time, ws2812, gpio
 
+      gpio.set_mode(gpio.WRISTBAND_2, gpio.mode.OUTPUT)
+
       i = 0
       while True:
           col1 = color.from_hsv(i % 360, 1.0, 0.1)