Update README.md

Add instructions on cloning the repo

Author: chesik-amd

README.md

@@ -10,6 +10,7 @@ is used by both CodeXL and GPU PerfStudio.
 * [Major Features](#Major)
 * [What's New](#WhatsNew)
 * [System Requirements](#System)
+* [Cloning the Repository](#Cloning)
 * [Source Code Directory Layout](#Source)
 * ["Public" vs "Internal" Versions](#PublicInternal)
 * [Building the Source Code](BUILD.md)
@@ -50,6 +51,15 @@ is used by both CodeXL and GPU PerfStudio.
 * Windows 7, 8.1, and 10
 * Ubuntu (14.04 and later) and RHEL (7 and later) distributions
 
+<A NAME="Cloning">
+## Cloning the Repository
+To clone the GPA repository, execute the following git commands
+ * git clone https://github.com/GPUOpen-Tools/GPA.git
+ * git submodule init
+ * git submodule update
+ * cd Common
+ * git checkout master
+
 <A NAME="Source">
 ## Source Code Directory Layout
 * [Build](GPUPerfAPI/Build) -- contains both Linux and Windows build-related files