add python 3 to path code example

Example 1: pip install python 3

You cannot just pip install python3 because it is not a library.

If you want to install the latest python3:
https://www.python.org/ftp/python/3.8.2/python-3.8.2.exe

Example 2: add python to path

To add Python to the Windows Path, follow these steps:

1. Start the Run box and enter sysdm.cpl
2. In the System Properties window go to the Advanced tab and 
   click the Environment Variables button
3. In the System variable window, find the Path variable and 
   click Edit
4. Position your cursor at the end of the Variable value line 
   and add the path to the python.exe file, preceeded with 
   the semicolon character (;)

Example 3: add python to path

# On linux
$ which python; # Get Path of the executable
$ export PATH=$PATH:{PATH_PYTHON}; # but it isn't continue
# ----------------------
$ which python; # Get Path of the executable
export PATH=$PATH:{PATH_PYTHON}; # add in your ~/.bashrc or your ~/.zshrc