fix ml intro

tensorflow_v2/notebooks/0_Prerequisite/mnist_dataset_intro.ipynb

@@ -25,10 +25,10 @@
    ]
   },
   {
-   "cell_type": "markdown",
-   "metadata": {
-    "collapsed": true
-   },
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
    "source": [
     "# Import MNIST\n",
     "from tensorflow.examples.tutorials.mnist import input_data\n",
@@ -49,10 +49,10 @@
    ]
   },
   {
-   "cell_type": "markdown",
-   "metadata": {
-    "collapsed": true
-   },
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
    "source": [
     "# Get the next 64 images array and labels\n",
     "batch_X, batch_Y = mnist.train.next_batch(64)"