[doc] update pp support (vllm-project#9853)

Signed-off-by: youkaichao <youkaichao@gmail.com>

docs/source/serving/distributed_serving.rst

@@ -22,7 +22,7 @@ After adding enough GPUs and nodes to hold the model, you can run vLLM first, wh
 Details for Distributed Inference and Serving
 ----------------------------------------------
 
-vLLM supports distributed tensor-parallel inference and serving. Currently, we support `Megatron-LM's tensor parallel algorithm <https://arxiv.org/pdf/1909.08053.pdf>`_.  We also support pipeline parallel as a beta feature for online serving. We manage the distributed runtime with either `Ray <https://github.com/ray-project/ray>`_ or python native multiprocessing. Multiprocessing can be used when deploying on a single node, multi-node inferencing currently requires Ray.
+vLLM supports distributed tensor-parallel and pipeline-parallel inference and serving. Currently, we support `Megatron-LM's tensor parallel algorithm <https://arxiv.org/pdf/1909.08053.pdf>`_. We manage the distributed runtime with either `Ray <https://github.com/ray-project/ray>`_ or python native multiprocessing. Multiprocessing can be used when deploying on a single node, multi-node inferencing currently requires Ray.
 
 Multiprocessing will be used by default when not running in a Ray placement group and if there are sufficient GPUs available on the same node for the configured :code:`tensor_parallel_size`, otherwise Ray will be used. This default can be overridden via the :code:`LLM` class :code:`distributed-executor-backend` argument or :code:`--distributed-executor-backend` API server argument. Set it to :code:`mp` for multiprocessing or :code:`ray` for Ray. It's not required for Ray to be installed for the multiprocessing case.
 
@@ -49,9 +49,6 @@ You can also additionally specify :code:`--pipeline-parallel-size` to enable pip
     $     --tensor-parallel-size 4 \
     $     --pipeline-parallel-size 2
 
-.. note::
-    Pipeline parallel is a beta feature. It is only supported for online serving as well as LLaMa, GPT2, Mixtral, Qwen, Qwen2, and Nemotron style models.
-
 Multi-Node Inference and Serving
 --------------------------------