Fixed doc URL in README (#962)

Author: sarahmaddox

mlengine/online-prediction/README.md

@@ -3,7 +3,7 @@
 ## Setup
 This sample demonstrates how to send online prediction requests to your deployed 
 model on CMLE. 
-Follow the [tutorial](https://cloud.google.com/ml-engine/docs/how-tos/deploying-models)
+Follow the [tutorial](https://cloud.google.com/ml-engine/docs/deploying-models)
 to deploy your model first.
 
 This sample is using the [Application Default Credential](https://developers.google.com/identity/protocols/application-default-credentials). You can install the Google Cloud SDK and run: