TEMPLATES Add rag-opensearch template (#13501)

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Adding rag-opensearch template.

---------

Signed-off-by: kalyanr <kalyan.ben10@live.com>
Co-authored-by: Erick Friis <erick@langchain.dev>

templates/rag-opensearch/rag_opensearch/__init__.py

@@ -0,0 +1,3 @@
+from rag_opensearch.chain import chain
+
+__all__ = ["chain"]