Update graph_optimization.ipynb for Intel Xeon 6 Processors

site/en/guide/graph_optimization.ipynb

@@ -101,7 +101,7 @@
         "* *Loop optimizer -* Optimizes the graph control flow by hoisting loop-invariant subgraphs out of loops and by removing redundant stack operations in loops. Also optimizes loops with statically known trip counts and removes statically known dead branches in conditionals.\n",
         "* *Scoped allocator optimizer -* Introduces scoped allocators to reduce data movement and to consolidate some operations.\n",
         "* *Pin to host optimizer -* Swaps small operations onto the CPU. This optimizer is turned OFF by default. \n",
-        "* *Auto mixed precision optimizer -* Converts data types to float16 where applicable to improve performance. Currently applies only to GPUs.\n",
+        "* *Auto mixed precision optimizer -* Converts data types to float16 where applicable to improve performance. Currently applies to GPUs and the latest Intel Xeon CPUs.\n",
         "* *Debug stripper -* Strips nodes related to debugging operations such as `tf.debugging.Assert`, `tf.debugging.check_numerics`, and `tf.print` from the graph. This optimizer is turned OFF by default."
       ]
     },