Fixed broken link (holoviz#3693)

examples/user_guide/Overview.ipynb

@@ -27,7 +27,7 @@
     "\n",
     "Panel is a very flexible system that supports many different usage patterns, via multiple application programming interfaces (APIs).  Each API has its own advantages and disadvantages, and is suitable for different tasks and ways of working. The [API user guide](APIs.ipynb) goes through each of the APIs in detail, comparing their pros and cons and providing recommendations on when to use each.\n",
     "\n",
-    "#### [Reactive functions](./APIs.ipynb#Reactive-Functions)\n",
+    "#### [Reactive functions](./APIs.ipynb#reactive-functions)\n",
     "\n",
     "Defining a reactive function using the ``pn.bind`` function or ``pn.depends`` decorator provides an explicit way to link specific inputs (such as the value of a widget) to some computation in a function, reactively updating the output of the function whenever the parameter changes. This approach is a highly convenient, intuitive, and flexible way of building interactive UIs.\n",
     "\n",