Plenty of documentation, and plenty of code that the AI can read itself.
E.g. if a library has a bug that has a common workaround, it can learn that from open source code using the library that uses the workaround.
E.g. if a library has a bug that has a common workaround, it can learn that from open source code using the library that uses the workaround.
Some of those discussions made people go figure out how to do it, and then post it as an answer. The knowledge didn't exist anywhere until they did.
Even if stuff isn't in the official documentation, eventually there are projects that use it.
And if the library in question is open-source, then the LLM's can just ingest and read that directly.