Newbie question: Why is it necessary to have both a "Document store", as well as a "Vector store"? When I look at the data contained inside of my vector store, it looks like it contains all of the node content that are also stored inside of the document store.
There are also a few features that rely on having quick access to all/specific documents (bm25, auto-merging retriever, etc.), where a docstore is helpful.
