langchain

805e9bfc - Add doc for the development of core and experimental sections (#13966)

Add doc for the development of core and experimental sections (#13966) ### **Description** Hi, I just started learning the source code of `langchain` and hope to contribute code. However, according to the instructions in the [CONTRIBUTING.md](https://github.com/langchain-ai/langchain/blob/master/.github/CONTRIBUTING.md) document, I could not run the test command `make test` to run normally. I found that many modules did not exist after [splitting `langchain_core`](https://github.com/langchain-ai/langchain/discussions/13823), so I updated the document. ### **Twitter handle** lin_bob57617