[Docs] Fix broken links (#2222)

docs/source/serving/serving_with_langchain.rst

@@ -28,4 +28,4 @@ To run inference on a single or multiple GPUs, use ``VLLM`` class from ``langcha
 
     print(llm("What is the capital of France ?"))
 
-Please refer to this `Tutorial <https://github.com/langchain-ai/langchain/blob/master/docs/extras/integrations/llms/vllm.ipynb>`_ for more details.
+Please refer to this `Tutorial <https://github.com/langchain-ai/langchain/blob/master/docs/docs/integrations/llms/vllm.ipynb>`_ for more details.