Update contribution readme

Author: Lou Amadio

README.md

@@ -1,9 +1,16 @@
 arduino-sdk
 ===========
 
-This repository contains the solution for the Arduino SDK components. 
+This repository contains the solution for the SDK from Arduino libraries. The purpose of this repository is to generate the Microsoft.IoT.SDKFromArduino nuget package. It is generated by leveraging Git submodules, importing the Arduino Github and packaging Arduino source files for inclusion in customer projects.
 
 # Contributing
-```git submodule init```
-```git submodule update```
+
+1. fork this repository. 
+1. Clone it to your local machine
+1. If you cloned your fork via the GitHub application, it will automatically initialize and update the submodule
+1. If you cloned your fork repository from a command line, you'll need to initialize sub-modules and update them
+
+   ```git submodule init```
+
+   ```git submodule update```