Fix link (#6501)

docs/extras/use_cases/question_answering/index.mdx

@@ -75,7 +75,7 @@ chain({"input_documents": docs, "question": query}, return_only_outputs=True)
 Additional related resources include:
 
 - [Building blocks for working with Documents](/docs/modules/data_connection/): Guides on how to use several of the utilities which will prove helpful for this task, including Text Splitters (for splitting up long documents) and Embeddings & Vectorstores (useful for the above Vector DB example).
-- [CombineDocuments Chains](/docs/modules/chains/documents/): A conceptual overview of specific types of chains by which you can accomplish this task.
+- [CombineDocuments Chains](/docs/modules/chains/document/): A conceptual overview of specific types of chains by which you can accomplish this task.
 
 ## End-to-end examples