Add more ledboard examples

docs/examples/led_board_5.py

@@ -0,0 +1,24 @@
+from gpiozero import LEDBoard
+from time import sleep
+
+leds = LEDBoard(2, 3, 4, 5, 6, 7, 8, 9)
+
+for led in leds[3:]:  # leds 3 and onward
+    led.on()
+sleep(1)
+leds.off()
+
+for led in leds[:2]:  # leds 0 and 1
+    led.on()
+sleep(1)
+leds.off()
+
+for led in leds[::2]:  # even leds (0, 2, 4...)
+    led.on()
+sleep(1)
+leds.off()
+
+for led in leds[1::2]:  # odd leds (1, 3, 5...)
+    led.on()
+sleep(1)
+leds.off()