Remove mention of going to / for the Endpoints sample. (GoogleCloudPlatform#573)

Since index.html has been removed, going to / is no longer a valid step.
Instead, the user should jump straight to calling the echo method.

Author: wmwong

appengine/flexible/endpoints/README.md

@@ -25,8 +25,6 @@ Run the application:
 $ python main.py
 ```
 
-In your web browser, go to the following address: http://localhost:8080.
-
 ### Using the echo client
 
 With the app running locally, you can execute the simple echo client using: