Correction: flexible -> standard (#1049)

Author: badersur

appengine/standard/django/README.md

@@ -1,7 +1,7 @@
 # Getting started with Django on Google Cloud Platform on App Engine Standard
 
 This repository is an example of how to run a [Django](https://www.djangoproject.com/) 
-app on Google App Engine Flexible Environment. It uses the 
+app on Google App Engine Standard Environment. It uses the 
 [Writing your first Django app](https://docs.djangoproject.com/en/1.9/intro/tutorial01/) as the 
 example app to deploy.