COMPMID-1008: Fix Doxygen issues

Change-Id: Ie73d8771f85d1f5b059f3a56f1bbd73c98e94a38
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/124723
Reviewed-by: Michalis Spyrou <michalis.spyrou@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/runtime/CL/functions/CLGEMM.h b/arm_compute/runtime/CL/functions/CLGEMM.h
index 2e82457..f2dd603 100644
--- a/arm_compute/runtime/CL/functions/CLGEMM.h
+++ b/arm_compute/runtime/CL/functions/CLGEMM.h
@@ -51,7 +51,10 @@
 class CLGEMM : public IFunction
 {
 public:
-    /** Default constructor. */
+    /** Default constructor.
+     *
+     * @param[in] memory_manager (Optional) Memory manager.
+     */
     CLGEMM(std::shared_ptr<IMemoryManager> memory_manager = nullptr);
     /** Initialise the kernel's inputs and output
      *