fix region tag

Author: andrewsg

appengine/standard/images/api/blobstore.py

@@ -56,10 +56,10 @@ def get(self):
             blob_info = blobstore.get(blob_key)
 
             if blob_info:
-# [START get_serving_url]
+                # [START get_serving_url]
                 url = images.get_serving_url(
                     blob_key, size=150, crop=True, secure_url=True)
-# [START get_serving_url]
+                # [END get_serving_url]
                 return webapp2.redirect(url)
 
         # Either "blob_key" wasn't provided, or there was no value with that ID