docs: add system architecture diagrams

[miketheman]

Not 100% comprehensive, but a good starting point.

Related to #2794

To see generated HTML, run:

make dev-docs && python -m http.server -d docs/dev/_build/html/

and browse to http://localhost:8000/architecture.html

[di]

The docs are also previewed here: https://warehouse--14241.org.readthedocs.build/architecture.html

[di]

The only thing missing here I think is that there should probably be a "Redis" component for uploads as well, because this is how we handle rate-limiting for all endpoints, including uploads.

[miketheman]

The only thing missing here I think is that there should probably be a "Redis" component for uploads as well, because this is how we handle rate-limiting for all endpoints, including uploads.

Added!

[di]

This looks good, but before we merge this... would it make more sense for this to be added to our docs at https://docs.pypi.org/ instead? I think we'd probably want to migrate it there eventually anyways, and looks like mkdocs supports Mermaid as well: https://squidfunk.github.io/mkdocs-material/reference/diagrams/

[miketheman]

would it make more sense for this to be added to our docs at docs.pypi.org instead?

I considered this, and didn't know the right answer. I thought about how most of the information is relevant to a warehouse developer (and others). The docs.pypi.org site seems more end-user-focused. I'm happy to put it whereever it makes most sense - but this felt more correct to me.

[di]

I think that delineation is good enough for me, for now. Thanks!