Update train-in-spark.ipynb

how-to-use-azureml/training/train-in-spark/train-in-spark.ipynb

@@ -8,6 +8,13 @@
         "\n",
         "Licensed under the MIT License."
       ]
+    },
+     {
+      "cell_type": "markdown",
+      "metadata": {},
+      "source": [
+          "![Impressions](https://PixelServer20190423114238.azurewebsites.net/api/impressions/MachineLearningNotebooks/how-to-use-azureml/training/train-in-spark/train-in-spark.png)"
+         ] 
     },
     {
       "cell_type": "markdown",
@@ -25,7 +32,7 @@
       "metadata": {},
       "source": [
         "## Prerequisites\n",
-        "Make sure you go through the [configuration notebook](../../../configuration.ipynb) first if you haven't."
+        "If you are using an Azure Machine Learning Notebook VM, you are all set. Otherwise, make sure you go through the [configuration notebook](../../../configuration.ipynb) first if you haven't."
       ]
     },
     {
@@ -275,4 +282,4 @@
   },
   "nbformat": 4,
   "nbformat_minor": 2
-}
+}