Add the ability to attach custom instructions to the Docs

I’ve found the RAG within Cursor a little limited when it comes to extracting useful information from the imported Docs.

It would be a great benefit to be able to attach custom instructions to any particular Doc set.

For instance, if you’re using a package like Pandas in Python, it would be useful to be able to provide an extra block of text as a custom prompt to guide the code generation. e.g. “Use .iloc() instead of .loc() when [some conditions are met].”