Description
Build up UML and sequence diagrams of the different parts of iTowns.
Context
Within the context of the TypeScript migration, a lot of the internal structure is not only bound but guaranteed to change. This would be the perfect time to create an ARCHITECTURE.md or similar to provide a clear overview of the library's internal structure and flow to contributors.
Description of the proposal
UML and sequence diagrams of the different parts of iTowns and sequence diagrams of the interactions between those parts.
Implementation
The file could either be built up over multiple PRs or created and discussed in one meta-PR that would only be merged at the end of the TypeScript migration.
I'm personally more keen on the former, as the latter will take additional maintenance work and is likely to get confusing over the months the full migration is going to take.
The diagrams can be created using mermaid.
Documentation
Variations of this already in use in other libraries: