Add small section about annotate internals

examples/user_guide/Annotators.ipynb

@@ -266,15 +266,49 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "point_annotator = annotate.instance()\n",
+    "point_annotate = annotate.instance()\n",
     "points = hv.Points([(500000, 500000), (1000000, 1000000)]).opts(size=10, color='red', line_color='black')\n",
-    "point_layout = point_annotator(points, annotations=['Label'])\n",
+    "point_layout = point_annotate(points, annotations=['Label'])\n",
     "\n",
-    "poly_annotator = annotate.instance()\n",
-    "poly_layout = poly_annotator(hv.Polygons([]), annotations=['Label'])\n",
+    "poly_annotate = annotate.instance()\n",
+    "poly_layout = poly_annotate(hv.Polygons([]), annotations=['Label'])\n",
     "\n",
     "annotate.compose(hv.element.tiles.Wikipedia(), point_layout, poly_layout)"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Internals\n",
+    "\n",
+    "The `annotate` function builds on param and [panel](https://panel.holoviz.org) and wraps `Annotator` panes internally. These objects make it easy to include the annotator in param based workflows and trigger actions when parameters change and/or update the annotator in response to external events. The Annotator of a `annotate` instance can be accessed using the `annotator` attribute:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(point_annotate.annotator)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This object can be included directly in a Panel layout, be used to watch for parameter changes, or updated directly:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "point_annotate.annotator.object = hv.Points(np.random.randn(10, 2)*1000000).opts(color='red')"
+   ]
   }
  ],
  "metadata": {