COMPMID-2973: Update documentation for exporting libOpenCL.so

In some platforms the OpenCL library might need to be exported in the
LD_LIBRARY_PATH in order to be "visible".

Change-Id: I8ac2e67258d0a4d2ddca3cb4eadce590d7433904
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2419
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
diff --git a/docs/02_tests.dox b/docs/02_tests.dox
index 81edcf2..37c318e 100644
--- a/docs/02_tests.dox
+++ b/docs/02_tests.dox
@@ -401,6 +401,7 @@
 
 	LD_LIBRARY_PATH=. ./arm_compute_benchmark --mode=precommit --filter="^CL.*" --instruments="opencl_timer_ms" --iterations=10
 
+@note You might need to export the path to OpenCL library as well in your LD_LIBRARY_PATH if Compute Library was build with OpenCL enabled.
 */
 } // namespace test
 } // namespace arm_compute