Fix examples link (quantumlib#2893)

docs/tutorial.ipynb

@@ -786,7 +786,7 @@
         "* Learn about the variety of [Gates](gates.ipynb) available in cirq and more about the different ways to construct [Circuits](circuits.ipynb)\n",
         "* Learn more about [Simulations](simulation.ipynb) and how it works.\n",
         "* Learn about [Noise](noise.ipynb) and how to utilize multi-level systems using [Qudits](qudits.ipynb)\n",
-        "* Dive into some [Examples](examples.md) and some case studies of how to use cirq.\n",
+        "* Dive into some [Examples](examples.rst) and some case studies of how to use cirq.\n",
         "\n",
         "Also, join our [cirq-announce mailing list](https://groups.google.com/forum/#!forum/cirq-announce) to hear about changes and releases or go to the [cirq github](https://github.com/quantumlib/Cirq/) to file issues."
       ]