[1.6.x] Fixed #20891 -- Removed part of the tutorial that requires pytz

Thanks AtomicSpark for the report.

Backport of 55339a7 from master

docs/intro/tutorial02.txt

@@ -385,15 +385,6 @@ search terms, Django will search the ``question`` field. You can use as many
 fields as you'd like -- although because it uses a ``LIKE`` query behind the
 scenes, keep it reasonable, to keep your database happy.
 
-Finally, because ``Poll`` objects have dates, it'd be convenient to be able to
-drill down by date. Add this line::
-
-    date_hierarchy = 'pub_date'
-
-That adds hierarchical navigation, by date, to the top of the change list page.
-At top level, it displays all available years. Then it drills down to months
-and, ultimately, days.
-
 Now's also a good time to note that change lists give you free pagination. The
 default is to display 100 items per page. Change-list pagination, search boxes,
 filters, date-hierarchies and column-header-ordering all work together like you