fix: resolve SKILL.md validation errors

skills/rag-implementation/SKILL.md

@@ -1,6 +1,8 @@
 ---
 name: rag-implementation
 description: "Build Retrieval-Augmented Generation (RAG) systems for LLM applications with vector databases and semantic search. Use when implementing knowledge-grounded AI, building document Q&A systems, or int..."
+risk: unknown
+source: community
 ---
 
 # RAG Implementation