fixing the example subsection that was raised to section

content/ch/16/ms_overfitting.ipynb

@@ -50,7 +50,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Example: Energy Consumption \n",
+    "## Example: Energy Consumption \n",
     "\n",
     "In this example, we examine a [dataset](https://www.key2stats.com/Utility_bills_1294_92.csv) that contains information from utility bills for a private residence in Minnesota. We have records of the monthly gas usage in a home (cubic feet) and the average temperature that month (degrees Farenheit).[^Kaplan] We first read in the data:\n",
     "\n",