Fix example name to avoid breaking collision with standard data-collectors

Author: Darien Hager

cookbook/profiler/data_collector.rst

@@ -67,7 +67,7 @@ populate the ``$this->data`` property (it takes care of serializing the
 
         public function getName()
         {
-            return 'memory';
+            return 'example_memory';
         }
     }