docs: added note for pre SYCL Intel hardware (#18016)

Specify that it's for pre sycl hardware

docs/backend/OPENCL.md

@@ -17,7 +17,7 @@ OpenCL (Open Computing Language) is an open, royalty-free standard for cross-pla
 
 ### Llama.cpp + OpenCL
 
-The llama.cpp OpenCL backend is designed to enable llama.cpp on **Qualcomm Adreno GPU** firstly via OpenCL. Thanks to the portabilty of OpenCL, the OpenCL backend can also run on certain Intel GPUs although the performance is not optimal.
+The llama.cpp OpenCL backend is designed to enable llama.cpp on **Qualcomm Adreno GPU** firstly via OpenCL. Thanks to the portabilty of OpenCL, the OpenCL backend can also run on certain Intel GPUs such as those that do not have [SYCL](/docs/backend/SYCL.md) support although the performance is not optimal.
 
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