[Doc]: Update tensorizer docs to include vllm[tensorizer] (#7889)

Co-authored-by: Kaunil Dhruv <dhruv.kaunil@gmail.com>

docs/source/serving/tensorizer.rst

@@ -10,3 +10,6 @@ shorter Pod startup times and CPU memory usage. Tensor encryption is also suppor
 For more information on CoreWeave's Tensorizer, please refer to
 `CoreWeave's Tensorizer documentation <https://github.com/coreweave/tensorizer>`_. For more information on serializing a vLLM model, as well a general usage guide to using Tensorizer with vLLM, see
 the `vLLM example script <https://docs.vllm.ai/en/stable/getting_started/examples/tensorize_vllm_model.html>`_.
+
+.. note::
+  Note that to use this feature you will need to install `tensorizer` by running `pip install vllm[tensorizer]`.