ENH: Set as template repository and/or move to .github repository

[rstoneback]

Description

A repository may officially be used to define template files used by default by other organization repositories.
https://docs.github.com/en/repositories/creating-and-managing-repositories/creating-a-template-repository

We could also create a .github repo and have it function in the same way, https://www.freecodecamp.org/news/how-to-use-the-dot-github-repository/ . Further, we can use a readme stored under profile to show up on the pysat organization landing page. Like here, https://github.com/microsoft .