Dockerize documentation so that it is easier and more consistent for new developers

[pacharanero]

• [x] Add Dockerfile to build a python environment and run mkdocs -serve
• [x] Add docker-compose.yml to enable use of docker compose up
• [x] Add scripts folder and s/up, s/down etc to facilitate running dev env
• [x] Document the above changes in the documentation about working on the documentation site