Merge pull request aws#351 from pigna90/add-note-xgboost

Added short note about validation channel

Author: djarpin

introduction_to_amazon_algorithms/xgboost_abalone/xgboost_abalone.ipynb

@@ -280,6 +280,13 @@
     "    print(status)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Note that the \"validation\" channel has been initialized too. The SageMaker XGBoost algorithm actually calculates RMSE and writes it to the CloudWatch logs on the data passed to the \"validation\" channel."
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -573,7 +580,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.2"
+   "version": "3.6.4"
   }
  },
  "nbformat": 4,