docs: include a dependencies navigator

[UlisesGascon]

Quite often when we need to do releases we need to follow a quite long process to prepare and publish sub-dependencies that we own. This process is even crucial when we do security releases as this help us to understand and prepare for patches propagation.

You can see the mermaid graph rendered (in a interactive way) using the Github UI (preview file):

Suggestions are more than welcome (cc: @expressjs/triagers @expressjs/express-tc) ❤️!

[jonchurch]

I've done some similar investigations in the past, but wasn't particularly interested in the graph relationship itself, so was always a flat list.

I'll share those here in case they're useful for building on top of:

Work to see what github orgs we depend on: https://gist.github.com/jonchurch/583964edf233225fc3bf79f1524545fa
Flat and naively deduped list of repos we depend on: https://gist.github.com/jonchurch/727735989d1985de2df645f10a73ffce

[Phillip9587]

I used npmgraph to identify dependencies and their versions. Maybe that helps: https://npmgraph.js.org/?q=express%405