Fixed typo in docs/ref/templates/api.txt.

docs/ref/templates/api.txt

@@ -371,10 +371,10 @@ replaced with the name of the invalid variable.
     While ``string_if_invalid`` can be a useful debugging tool, it is a bad
     idea to turn it on as a 'development default'.
 
-    Many templates, including some of the Django's templates, rely upon the
-    silence of the template system when a nonexistent variable is encountered.
-    If you assign a value other than ``''`` to ``string_if_invalid``, you will
-    experience rendering problems with these templates and sites.
+    Many templates, including some of Django's, rely upon the silence of the
+    template system when a nonexistent variable is encountered. If you assign a
+    value other than ``''`` to ``string_if_invalid``, you will experience
+    rendering problems with these templates and sites.
 
     Generally, ``string_if_invalid`` should only be enabled in order to debug
     a specific template problem, then cleared once debugging is complete.