Visualization of the detectron2 codebas

First of all, thanks to [@Vishnu8299](https://github.com/Vishnu8299) for the kind and thoughtful response on the original discussion (https://github.com/facebookresearch/detectron2/discussions/5473). Based on the positive feedback, I’d like to propose a small documentation improvement for Detectron2: integrating a visual onboarding diagram to help new contributors and users better understand the structure of the codebase.

As someone passionate about open source, I’ve often found onboarding into complex projects overwhelming. Our goal is to ease that process by generating diagrams that give a high-level overview of the architecture, main modules, and flow within the codebase.

We’ve created a diagram which you cna preview here: https://github.com/CodeBoarding/GeneratedOnBoardings/blob/main/detectron2/on_boarding.md that aims to do just that. Before opening a PR, I wanted to collect feedback here from maintainers and contributors:

Would a diagram like this be a helpful addition to the official docs?

Would you prefer this be linked from the README, GETTING_STARTED.md, or the sphinx doc generation?

We also have a free github action which will keep the diagrams up-to-date and I can integrate it so that it updates them in your prefered doc style i.e. part of the sphinx doc generation.

Full disclosure: we are in the very early stages of turning this into a startup focused on improving open source onboarding — but our current priority is making sure this genuinely helps communities like this one.

Happy to iterate based on feedback and open a PR if there’s interest and also super interested to connect and discuss how we can help!

Review the proposed diagram in GeneratedOnBoardings/detectron2/on_boarding.md and compare the possible integration points named in the issue: README, GETTING_STARTED.md, or Sphinx documentation generation. The work is not ready to start until maintainers choose whether the diagram belongs in the official docs and define the preferred update mechanism and documentation style.

Written by the indexing model from the issue text.