Add GPU device configuration instructions for vLLM OpenVINO backend

Author: sshlyapn

docs/source/getting_started/openvino-installation.rst

@@ -59,6 +59,8 @@ Install from source
 
       $ PIP_EXTRA_INDEX_URL="https://download.pytorch.org/whl/cpu https://storage.openvinotoolkit.org/simple/wheels/pre-release" VLLM_TARGET_DEVICE=openvino python -m pip install -v .
 
+- [Optional] To use vLLM OpenVINO backend with a GPU device, ensure your system is properly set up. Follow the instructions provided here: `https://docs.openvino.ai/2024/get-started/configurations/configurations-intel-gpu.html <https://docs.openvino.ai/2024/get-started/configurations/configurations-intel-gpu.html>`_.
+
 .. _openvino_backend_performance_tips:
 
 Performance tips