Fixed #17490 -- Added a trailing comma in INSTALLED_APPS, to avoid unexpected string concatenation when adding another app.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17324 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/intro/tutorial01.txt

@@ -414,7 +414,7 @@ it'll look like this::
         'django.contrib.contenttypes',
         'django.contrib.sessions',
         'django.contrib.sites',
-        'polls'
+        'polls',
     )
 
 Now Django knows to include the ``polls`` app. Let's run another