Docs suggestion: add a compact RAG failure mode taxonomy checklist for incident triage

Hi R2R maintainers, thanks for the engineering focus.

Proposal Add a compact “RAG failure mode taxonomy checklist” to docs:

• symptom -> one code (16 total) -> minimal checks -> minimal fixes

Why It helps teams stop repeating the same classes of failures across chunking, embeddings, retrieval, reranking, agent flow, and deployment ordering.

Reference taxonomy WFGY Problem Map (No 1 to No 16): https://github.com/onestardao/WFGY/blob/main/ProblemMap/README.md

Scope Docs-only. If you like the idea, I can draft the first version quickly and open a PR.