Updating ReadMe

Including a note that the guide should work fine with Pi 1 and Pi 3 as
well. Closes #36

README.md

@@ -14,6 +14,8 @@ ___
 ### Hardware you need
 
 1. **Raspberry Pi 2 (Model B)**  - [Buy at Amazon](http://amzn.com/B00T2U7R7I)
+UPDATE: Even though this guide was built using a Raspberry Pi 2, it should work just fine with a Pi 3 & Pi 1 as well. See [this](https://github.com/amzn/alexa-avs-raspberry-pi/issues/36) and [this](https://github.com/amzn/alexa-avs-raspberry-pi/issues/2).
+
 2. **Micro-USB power cable** for Raspberry Pi (included with Raspberry Pi)
 3. **Micro SD Card** - To get started with Raspberry Pi you need an operating system. NOOBS (New Out Of the Box Software) is an easy-to-use operating system install manager for the Raspberry Pi. The simplest way to get NOOBS is to buy an SD card with NOOBS preinstalled - [Raspberry Pi 8GB Preloaded (NOOBS) Micro SD Card](https://www.amazon.com/gp/product/B00ENPQ1GK/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1) 
 4. An **Ethernet cable**