Document project interlinking

### What is the problem or limitation you are having?

Different BeeWare projects depend on each other, and we don't have a good picture of this interconnectivity documented at the moment.

### Describe the solution you'd like

We need to provide a way for a new user to understand how all the pieces fit together. This might be a diagram of the "tech stack", showing how all the pieces fit together - or it could be a narrative description of the relationships.

### Describe alternatives you've considered

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### Additional context