We need to make the documentation more detailed on how to build the project. This is important for contributors. This includes:

• Build instructions using the buildenv docker image. Probably the easiest way to get going building the project, as all the environment/dependencies are already set up.
• A more detailed summary of the structure of the code base.
• How the workflow for building documentation works
• Building on Windows. Related to #666. Need to remove old instructions here: (Windows-Building.md)[Windows-Building.md].

This documentation should be in a markdown document in the root of the repository, rather than in the documentation site. (The doc site is more intended for users of the mod, and having it on there adds extra overhead in terms of updating it)