Add WFGY ProblemMap (RAG/LLM debugging toolkit) to textual techniques

[onestardao]

Hi, and thanks for maintaining this repo – it has become a very useful entry point for people working on financial ML and data pipelines.

This PR adds WFGY ProblemMap to the Techniques → Textual section.

• Repo: https://github.com/onestardao/WFGY
• What it is: an MIT-licensed “semantic firewall” / debugging toolkit for LLM + RAG pipelines, built as a 16-problem taxonomy of failure modes (data ingestion, embeddings + vector stores, retrievers, routing, evaluation).
• Why it fits here: many projects in this list now include research assistants, report generators or document QA based on financial text. ProblemMap is used as a practical checklist to harden those pipelines before they go into production.
• Academic / research references: WFGY’s ProblemMap has already been referenced or integrated by:
  • Harvard MIMS Lab’s ToolUniverse
  • QCRI LLM Lab’s Multimodal-RAG-Survey

If you prefer a different wording or placement (e.g. another section), I’m happy to adjust.