docs: update contributing project structure

[oddgrd]

Description of change

Update the contributing section on project structure with the major changes from the last few releases.

TODO:

• update the mermaid graph, or find an alternative that also works in the mintlify docs (updated but it's not very pretty, we should consider improving it in a future PR).
• expand on some of the binaries, at least auth.

seems you still have TODOs left. waiting on those as well.