docs/esp8266/tutorial: Update neopixel with example of using 4 bbp.

docs/esp8266/tutorial/neopixel.rst

@@ -20,6 +20,20 @@ To set the colour of pixels use::
     >>> np[1] = (0, 128, 0) # set to green, half brightness
     >>> np[2] = (0, 0, 64)  # set to blue, quarter brightness
 
+For LEDs with more than 3 colours, such as RGBW pixels or RGBY pixels, the
+NeoPixel class takes a ``bpp`` parameter. To setup a NeoPixel object for an
+RGBW Pixel, do the following::
+
+    >>> import machine, neopixel
+    >>> np = neopixel.NeoPixel(machine.Pin(4), 8, bpp=4)
+
+In a 4-bpp mode, remember to use 4-tuples instead of 3-tuples to set the colour.
+For example to set the first three pixels use::
+
+    >>> np[0] = (255, 0, 0, 128) # Orange in an RGBY Setup
+    >>> np[1] = (0, 255, 0, 128) # Yellow-green in an RGBY Setup
+    >>> np[2] = (0, 0, 255, 128) # Green-blue in an RGBY Setup
+
 Then use the ``write()`` method to output the colours to the LEDs::
 
     >>> np.write()