Remove go/ link from colab.ipynb (#3963)

go/ links should not be used externally.

docs/tutorials/google/colab.ipynb

@@ -159,7 +159,7 @@
    "source": [
     "## Authenticate and install Cirq\n",
     "\n",
-    "For details of authentication and installation, please see [go/quantum-engine-quickstart](http://go/quantum-engine-quickstart). \n",
+    "For details of authentication and installation, please see [Get started with Quantum Computing Service](start.ipynb).\n",
     "\n",
     "Note:  The below code will install the latest stable release of cirq.  If you need the latest and greatest features and don't mind if a few things aren't quite working correctly, you can install the pre-release version of `cirq` using `pip install --pre cirq` instead of `pip install cirq` to get the most up-to-date features of cirq.\n",
     "\n",