Provide a visual description of the Executable Books stack, its components, and how they fit together

[choldgraf]

Context

We now have many different projects at various levels of the stack. Some of these are building blocks, some of them are high-level integrators of those building blocks. Some are for end-users, some are more developer-facing. It is hard to navigate all of these projects, understand how they fit together, etc.

We describe the tools in the stack here as well as in jupyter book but neither does a good job of explaining how all the pieces fit together.

We have an excalidraw draft of the Jupyter Book stack here. It just hasn't been added yet.

Proposal

We should provide a centralized documentation that shows off the major parts of the Python/Sphinx stack, as well as the major parts of the JavaScript/MySTJS stack. These should provide a way for people to quickly understand how the pieces fit together, and have pointers to more in-depth docs for each component.