I would think that Dashbit’s libraries are pretty good examples of how to go about things, for example: GitHub - elixir-broadway/broadway: Concurrent and multi-stage data ingestion and data processing with Elixir · GitHub
Note the guides and the docs function in mix.exs - useful docs are one of the most important aspects of a library (assuming it actually works and has a sensible API 
). Also note the inline docs in the code and typespecs for any public functions in the library.
