Fixed #23535 -- Updated tutorial to account for default filter added in 5ea34f3f.

docs/intro/tutorial02.txt

@@ -511,11 +511,12 @@ template directory in the source code of Django itself
         import django
         print(django.__path__)"
 
-Then, just edit the file and replace ``{{ site_header }}`` with your own
-site's name as you see fit. We use this approach to teach you how to override
-templates. In an actual project, you would probably use the
-:attr:`django.contrib.admin.AdminSite.site_header` attribute to more easily
-make this particular customization.
+Then, just edit the file and replace
+``{{ site_header|default:_('Django administration') }}`` with your own site's
+name as you see fit, e.g. ``{{ _('Polls administration') }}``. We use this
+approach to teach you how to override templates. In an actual project, you
+would probably use the :attr:`django.contrib.admin.AdminSite.site_header`
+attribute to more easily make this particular customization.
 
 This template file contains lots of text like ``{% block branding %}``
 and ``{{ title }}``. The ``{%`` and ``{{`` tags are part of Django's