docs: Add additional badges based on pypi package information

There are also badges available for things like downloads on pypi
and other items, but these seem the most useful in general.  It's
a nice way to see the currently published version on pypi as
well as calling out the license/supported versions.

You can see other badges based on pypi info at https://pypip.in/.   What do you think @tpmanley and @swstack