Small bug fix in pcovr regressor example

Author: rosecers

examples/PCovR_Regressors.ipynb

@@ -1,5 +1,13 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "9eb06ac4",
+   "metadata": {},
+   "source": [
+    "# Choosing Different Regressors for PCovR"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,
@@ -48,7 +56,7 @@
    "id": "87b32d6e",
    "metadata": {},
    "source": [
-    "# Use the default regressor in PCovR"
+    "## Use the default regressor in PCovR"
    ]
   },
   {
@@ -93,7 +101,7 @@
    "id": "c3500b70",
    "metadata": {},
    "source": [
-    "# Use a fitted regressor"
+    "## Use a fitted regressor"
    ]
   },
   {
@@ -157,7 +165,7 @@
    "id": "6699c0d6",
    "metadata": {},
    "source": [
-    "# Use a pre-predicted y"
+    "## Use a pre-predicted y"
    ]
   },
   {
@@ -230,7 +238,7 @@
    "id": "c8677465",
    "metadata": {},
    "source": [
-    "# Comparing Results"
+    "## Comparing Results"
    ]
   },
   {