feat: support for moi in RAG module (#571)

* feat: add support for moi

* small adjust

* small adjust

* according 2 comments

* add more intro

* add more intro

src/rag/__init__.py

@@ -3,6 +3,7 @@
 
 from .builder import build_retriever
 from .ragflow import RAGFlowProvider
+from .moi import MOIProvider
 from .retriever import Chunk, Document, Resource, Retriever
 from .vikingdb_knowledge_base import VikingDBKnowledgeBaseProvider
 
@@ -11,6 +12,7 @@ __all__ = [
     Document,
     Resource,
     RAGFlowProvider,
+    MOIProvider,
     VikingDBKnowledgeBaseProvider,
     Chunk,
     build_retriever,