docs updated (#2976)

* docs updated

* addressing comments

* add missing $

* removing trailing whitespace

docs/Using-Virtual-Environment.md

 to run ML-Agents on (either local laptop/desktop or remote server). Python 3.6 can be
 installed from [here](https://www.python.org/downloads/).
 
+## Python Version Requirement (Required)
+This guide has been tested with Python 3.6 and 3.7. Python 3.8 is not supported at this time.
 
 ## Installing Pip (Required)
 
 1. To create a new environment named `sample-env` execute `$ python3 -m venv ~/python-envs/sample-env`
 1. To activate the environment execute `$ source ~/python-envs/sample-env/bin/activate`
 1. Verify pip version is the same as in the __Installing Pip__ section. In case it is not the latest, upgrade to
-the latest pip version using `pip3 install --upgrade pip`
+the latest pip version using `$ pip3 install --upgrade pip`
 1. Install ML-Agents package using `$ pip3 install mlagents`
 1. To deactivate the environment execute `$ deactivate`
 
 
 ## Windows Setup
 
-1. Create a folder where the virtual environments will reside `$ md python-envs`
-1. To create a new environment named `sample-env` execute `$ python3 -m venv python-envs\sample-env`
-1. To activate the environment execute `$ python-envs\sample-env\Scripts\activate`
-1. Verify pip version is the same as in the __Installing Pip__ section. In case it is not the latest, upgrade to
-the latest pip version using `pip3 install --upgrade pip`
-1. Install ML-Agents package using `$ pip3 install mlagents`
-1. To deactivate the environment execute `$ deactivate`
+1. Create a folder where the virtual environments will reside `md python-envs`
+1. To create a new environment named `sample-env` execute `python -m venv python-envs\sample-env`
+1. To activate the environment execute `python-envs\sample-env\Scripts\activate`
+1. Verify pip version is the same as in the __Installing Pip__ section. In case it is not the
+latest, upgrade to the latest pip version using `pip install --upgrade pip`
+1. Install ML-Agents package using `pip install mlagents`
+1. To deactivate the environment execute `deactivate`
+
+Note:
+- Verify that you are using Python 3.6 or Python 3.7. Launch a command prompt using `cmd` and
+ execute `python --version` to verify the version.
+- Python3 installation may require admin privileges on Windows.
+- This guide is for Windows 10 using a 64-bit architecture only.