Update README.md (GoogleCloudPlatform#4180)

averikitsch · web-flow · commit caa200f6fa02 · 2020-11-05T08:41:01.000-08:00
diff --git a/README.md b/README.md
@@ -30,7 +30,7 @@ README files for details.
     Or manually set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable
     to point to a service account key JSON file path.
 
-    Learn more at [Setting Up Authentication for Server to Server Production Applications](ADC).
+    Learn more at [Setting Up Authentication for Server to Server Production Applications][ADC].
 
     *Note:* Application Default Credentials is able to implicitly find the credentials as long as the application is running on Compute Engine, Kubernetes Engine, App Engine, or Cloud Functions.
 
