You can build the documentation system locally without either Docker or LXD if you like. If you elect to use this procedure however, be aware that if you do a lot of Python coding or use Python locally, your safest bet is to create a Python Virtual Environment described here. This keeps all of your Python processes protected from each other, which is recommended. If you choose to use this procedure without the Python Virtual Environment, then just be aware that you are taking a certain amount of risk.
This provides a quick and simple way to run a local copy of documentation without Docker or LXD. If you choose this method, you should really setup a Python Virtual Environment to protect your other Python processes.