Fix README.md

Author: Frank Natividad

appengine-java8/endpoints-v2-backend/README.md

@@ -41,7 +41,7 @@ To deploy the sample API:
 
 0. Invoke the `gcloud` command to deploy the API configuration file:
 
-         gcloud service-management deploy openapi.json
+         gcloud service-management deploy target/openapi-docs/openapi.json
 
 0. Deploy the API implementation code by invoking: