Multi-version documentation
Keep the documentation for old versions. So that the API of old versions can still be found and used. That might not be important for the alpha stage, but should be done at last with version 1.0.
There seem to be some sphinx-extensions which can handle this, but many of them are unmaintained. This one is the most active that I was able to find: https://holzhaus.github.io/sphinx-multiversion/master/index.html