esbuild and Redis1 are two examples of codebases with exceptional documentation.
Through their READMEs, changelogs, architecture documents, and code comments, both projects explain their design in such a way that someone new to the codebase can understand where things are, how things are done, and why they are done that way.
If you’re a developer looking to get better at documenting your code and software architecture, these are great case studies.
Bevan-wallace
Source-initiative
Open-source-initiative