BuildTheDocs
A Sphinx documentation building tool on steroids.
BuildTheDocs is a tool which helps building Sphinx documentation for multiple versions of a project. It builds the documentation of multiple versions with only one command, while customizing the documentation, for example adding a simple version chooser.
It’s also licensed under the MIT license, allowing you to customize it as you wish.
If you want to learn more about it, you should start reading the documentation.