[1.2.X] Changed ModelForm.fields and ModelForm.exclude examples to use tuples instead of lists since they were used inconsistently throughout the page (it wasn't hurting anything, but consistency is nice). Thanks to lspcity for the report and gruszczy for the patch.

Backport of [14134] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14135 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/topics/forms/modelforms.txt

@@ -387,7 +387,7 @@ widget::
     class AuthorForm(ModelForm):
         class Meta:
             model = Author
-            fields = ['name', 'title', 'birth_date']
+            fields = ('name', 'title', 'birth_date')
             widgets = {
                 'name': Textarea(attrs={'cols': 80, 'rows': 20}),
             }
@@ -471,7 +471,7 @@ to be rendered first, we could specify the following ``ModelForm``::
     >>> class BookForm(ModelForm):
     ...     class Meta:
     ...         model = Book
-    ...         fields = ['title', 'author']
+    ...         fields = ('title', 'author')
 
 .. _overriding-modelform-clean-method:
 
@@ -514,7 +514,7 @@ the ``Meta.fields`` or ``Meta.excludes`` lists::
 
     >>> class RestrictedArticleForm(EnhancedArticleForm):
     ...     class Meta(ArticleForm.Meta):
-    ...         exclude = ['body']
+    ...         exclude = ('body',)
 
 This adds the extra method from the ``EnhancedArticleForm`` and modifies
 the original ``ArticleForm.Meta`` to remove one field.