Update instructions for setting up TF Sharp (#186)

Summary of changes in setting up TF Sharp
1) Make sure to press "enter" after entering "ENABLE_TENSORFLOW" flag.  
2) Save the project.
3) Checking to make sure the TF asset files are installed in the project.

docs/Getting-Started-with-Balance-Ball.md

 Because TensorFlowSharp support is still experimental, it is disabled by default. In order to enable it, you must follow these steps. Please note that the `Internal` Brain mode will only be available once completing these steps.
 
 1. Make sure you are using Unity 2017.1 or newer.
-2. Make sure the TensorFlowSharp plugin is in your `Assets` folder. A Plugins folder which includes TF# can be downloaded [here](https://s3.amazonaws.com/unity-agents/0.2/TFSharpPlugin.unitypackage). Double click and import it once downloaded.
+2. Make sure the TensorFlowSharp plugin is in your `Assets` folder. A Plugins folder which includes TF# can be downloaded [here](https://s3.amazonaws.com/unity-agents/0.2/TFSharpPlugin.unitypackage). Double click and import it once downloaded.  You can see if this was successfully installed by checking the TensorFlow files in the Project tab under `Assets` -> `ML-Agents` -> `Plugins` -> `Computer`
-	3. In `Scripting Defined Symbols`, add the flag `ENABLE_TENSORFLOW`
-5. Restart the Unity Editor.
+	3. In `Scripting Defined Symbols`, add the flag `ENABLE_TENSORFLOW`.  After typing in, press Enter.
+5. Go to `File` -> `Save Project`
+6. Restart the Unity Editor.
 
 ### Embedding the trained model into Unity