update comment and markdown on region and role

Author: andremoeller

sagemaker-spark/pyspark_mnist/xgboost_mnist.ipynb

@@ -42,13 +42,17 @@
     "\n",
     "First, we load the MNIST dataset into a Spark Dataframe, which dataset is available in LibSVM format at\n",
     "\n",
-    "s3://sagemaker-sample-data-[region, such as us-east-1]/spark/mnist/train/"
+    "`s3://sagemaker-sample-data-[region]/spark/mnist/train/`\n",
+    "\n",
+    "where `[region]` is replaced with a supported AWS region, such as us-east-1"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "from pyspark import SparkContext, SparkConf\n",
@@ -76,7 +80,9 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# replace this with your own region, such as us-east-1\n",
@@ -129,14 +135,15 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "import random\n",
     "from sagemaker_pyspark import IAMRole, S3DataPath\n",
     "from sagemaker_pyspark.algorithms import XGBoostSageMakerEstimator\n",
     "\n",
-    "# replace this with your role ARN\n",
     "xgboost_estimator = XGBoostSageMakerEstimator(\n",
     "    sagemakerRole=IAMRole(role),\n",
     "    trainingInstanceType='ml.c4.2xlarge',\n",
@@ -219,7 +226,9 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "# Delete the endpoint\n",