Imporvements to Installation guide

- Including Jupyter notebook guide.

docs/Background-Jupyter.md

 # Jupyter
 
-**Work In Progress**
-
-embedded visualizations. We provide several such notebooks for testing your 
-Python installation and training behaviors. For a walkthrough of how to use 
-Jupyter, see
+embedded visualizations. We provide one such notebook, `Basics.ipynb`, for 
+testing the Python API. 
+
+For a walkthrough of how to use Jupyter, see
-in the _Jupyter/IPython Quick Start Guide_.
-
-To launch Jupyter, run in the command line:
+in the _Jupyter/IPython Quick Start Guide_. To launch Jupyter, run in the command line:
-Then navigate to `localhost:8888` to access the notebooks.
+Then navigate to `localhost:8888` to access your notebooks.

docs/Installation.md

 to add to your projects. The `python` directory contains the training code.
 Both directories are located at the root of the repository. 
 
-## Install Python
+## Install Python (with Dependencies)
 
 In order to use ML-Agents, you need Python (2 or 3; 64 bit required) along with
 the dependencies listed in the [requirements file](../python/requirements.txt).
+
+We **strongly** recommend using Python 3 as we do not guarantee supporting Python 2
+in future releases. In all of our subsequent instructions, we use `python` 
+to refer to either Python 2 or 3, depending on your installation.
 
 ### Windows Users