update venv python code example

Example 1: python env

python3 -m venv tutorial-env
tutorial-env\Scripts\activate.bat (window)
source tutorial-env/bin/activate (linux)

Example 2: python virtualenv venv

python -m venv venv

Example 3: create a virtualenv python3

py -m venv env

Example 4: how to activate the pytho virtual environment

mypthon\Scripts\activate