improve intro example (#4652)

Co-authored-by: Marc Skov Madsen <[email protected]>

examples/homepage.ipynb

@@ -65,17 +65,24 @@
     "\"\"\")\n",
     "\n",
     "code = pn.widgets.CodeEditor(language='python', theme='monokai', height=360, value=\\\n",
-    "\"\"\"x = pn.widgets.Select(name='x', options=cols)\n",
+    "\"\"\"import panel as pn\n",
+    "\n",
+    "pn.extension()\n",
+    "\n",
+    "x = pn.widgets.Select(name='x', options=cols)\n",
     "y = pn.widgets.Select(name='y', options=cols, value='bill_depth_mm')\n",
     "n_clusters = pn.widgets.IntSlider(name='n_clusters', start=2, end=5, value=3)\n",
+    "\n",
     "explanation = pn.pane.Markdown(...)\n",
     "\n",
-    "def plot_clusters(x, y, n_clusters):\n",
+    "def plot(x, y, n_clusters):\n",
     "    ...\n",
     "    \n",
+    "interactive_plot = pn.bind(plot, x, y, n_clusters)\n",
+    "    \n",
     "pn.Row(\n",
     "    pn.WidgetBox(x, y, n_clusters, explanation),  \n",
-    "    pn.bind(plot, x, y, n_clusters)\n",
+    "    interactive_plot\n",
     ")\"\"\", width=800)\n",
     "\n",
     "app = pn.Tabs(\n",