update python pip command code example

Example 1: upgrade pip

python -m pip install --upgrade pip

Example 2: command to upgrade python version

python -m pip install pip
#or
python -m pip install –upgrade pip
python -m pip install --upgrade pip

Example 3: 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