Fixed confusion matrix normalization issue.

Author: MedAymenF

site/en/guide/core/mlp_core.ipynb

@@ -933,7 +933,7 @@
         "  plt.figure(figsize=(10,10))\n",
         "  confusion = sk_metrics.confusion_matrix(test_labels.numpy(), \n",
         "                                          test_classes.numpy())\n",
-        "  confusion_normalized = confusion / confusion.sum(axis=1)\n",
+        "  confusion_normalized = confusion / confusion.sum(axis=1, keepdims=True)\n",
         "  axis_labels = range(10)\n",
         "  ax = sns.heatmap(\n",
         "      confusion_normalized, xticklabels=axis_labels, yticklabels=axis_labels,\n",