Sets QUESTIONNAIRE_USE_SESSION in the example.

Includes a brief explanation of how the setting changes the app
behavior.

example/settings.py

@@ -146,5 +146,12 @@ LANGUAGES = (
 #   questionnaire is so huge that even the ajax request takes too long.
 QUESTIONNAIRE_PROGRESS = 'async'
 
+# Defines how the questionnaire and questionset id are passed around.
+# If False, the default value, the ids are part of the URLs and visible to the
+# user answering the questions.
+# If True the ids are set in the session and the URL remains unchanged as the
+# user goes through the steps of the question set.
+QUESTIONNAIRE_USE_SESSION = False
+
 try: from local_settings import *
 except: pass