Added usage instructions

Author: crimsonred

README.md

@@ -6,6 +6,12 @@
 ### Supports PC, Mac, Linux, iOS, Android, Windows Store Universal 10 and WebGL
 
 ## All new PubNub Unity SDK
+### Usage
+  * Downloaded the PubNub.unitypackage from the [latest release](https://github.com/pubnub/unity/releases/latest)
+  * Import it to your Unity project by going to Assets -> Import Package -> Custom Package. 
+  * Now that your PubNub Unity Package has been imported, you must enable it in the Test Runner. To enable the PubNub Unity Package, go to Window -> Test Runner. Click on the mini drop down menu next to the window close button, and click Enable playmode tests for all assemblies. 
+  * You will have to restart your Unity editor to finalize these changes. 
+  * Congrats, you are now all setup to start using the PubNub Unity SDK!
 ### DOCS 
   * https://www.pubnub.com/docs/unity3d-c-sharp/pubnub-c-sharp-sdk-v4