pwm: Added python example script

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>

examples/python/cycle-pwm3.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+
+import pymaa as maa
+import time
+
+x = maa.PWM(0,3)
+x.enable(1);
+x.period_us(20)
+value= 0.0
+
+while True:
+    x.write(value)
+    time.sleep(0.2)
+    value = value +0.01
+    if value >= 1:
+        value = 0.0