Update data_performance.ipynb

Author: RenuPatelGoogle

site/en/guide/data_performance.ipynb

@@ -274,7 +274,6 @@
       "source": [
         "### Prefetching\n",
         <a name="prefetching">
-
         "\n",
         "Prefetching overlaps the preprocessing and model execution of a training step.\n",
         "While the model is executing training step `s`, the input pipeline is reading the data for step `s+1`.\n",