Document how to install Python on MacOS

[maltfield]

Is your feature request related to a problem? Please describe.

This is a request to update the documentation to include how to actually install Python on MacOS after downloading the .pkg file

• https://docs.python.org/3/using/mac.html#getting-and-installing-python

Describe the solution you'd like

The documentation should include the commands to run to install the .pkg file and to then open a python interpreter to get a shell in python.

Additional context

This is especially confounding on headless systems. The docs say how to download, but then jump to What you get after installing without saying how the heck you actually do the install...