Add pwm examples

pwm/led.py

@@ -0,0 +1,15 @@
+from machine import Pin
+from machine import PWM
+from time import sleep
+
+led = PWM(Pin(0, Pin.OUT))
+
+for i in range(-1, 1024, 8):
+    led.duty(i)
+    print(i)
+    sleep(0.1)
+    
+for i in range(1023, -1, -8):
+    led.duty(i)
+    print(i)
+    sleep(0.1)

pwm/rgb.py

@@ -0,0 +1,17 @@
+from machine import Pin
+from time import sleep
+
+blue = Pin(0, Pin.OUT)
+green = Pin(4, Pin.OUT)
+red = Pin(5, Pin.OUT)
+
+blue.off()
+red.on()
+sleep(1)
+red.off()
+green.on()
+sleep(1)
+green.off()
+blue.on()
+sleep(1)
+blue.off()