Simplified a coding style example in docs/contributing.txt from [5264]

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5265 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/contributing.txt

@@ -348,8 +348,8 @@ Model style
       Don't do this::
 
           class Person(models.Model):
-              FirstName = models.CharField(maxlength=20)
-              Last_Name = models.CharField(maxlength=40)
+              first_name = models.CharField(maxlength=20)
+              last_name = models.CharField(maxlength=40)
               class Meta:
                   verbose_name_plural = 'people'
 
@@ -359,8 +359,8 @@ Model style
               class Meta:
                   verbose_name_plural = 'people'
 
-              FirstName = models.CharField(maxlength=20)
-              Last_Name = models.CharField(maxlength=40)
+              first_name = models.CharField(maxlength=20)
+              last_name = models.CharField(maxlength=40)
 
     * The order of model inner classes and standard methods should be as
       follows (noting that these are not all required):