Updated Models to include Pi 3 A+

Author: drewszurko

README.md

@@ -31,6 +31,7 @@ The complete collection of (consumer) Raspberry Pi models consist of:
 - [Raspberry Pi 3, Model B](https://www.raspberrypi.org/products/raspberry-pi-3-model-b/) (March, 2016)
 - [Raspberry Pi Zero W](https://www.raspberrypi.org/products/raspberry-pi-zero-w/) (February, 2017)
 - [Raspberry Pi 3, Model B+](https://www.raspberrypi.org/products/raspberry-pi-3-model-b-plus/) (March, 2018)
+- [Raspberry Pi 3, Model A+](https://www.raspberrypi.org/products/raspberry-pi-3-model-a-plus/) (November, 2018)
 
 ## OS Images