Added a rainbow example

examples/rainbow.py

@@ -0,0 +1,21 @@
+import time
+import ws2812b
+
+numpix = 30
+strip = ws2812b.ws2812b(numpix, 0,0)
+
+RED = (255, 0, 0)
+ORANGE = (255, 165, 0)
+YELLOW = (255, 150, 0)
+GREEN = (0, 255, 0)
+BLUE = (0, 0, 255)
+INDIGO = (75, 0, 130)
+VIOLET = (138, 43, 226)
+COLORS = (RED, ORANGE, YELLOW, GREEN, BLUE, INDIGO, VIOLET)
+
+while True:
+    for color in COLORS:
+        for i in range(numpix):
+            strip.set_pixel(i, color[0], color[1], color[2])
+            time.sleep(0.01)
+            strip.show()