Fixed the typo mentioned in issue #1431

Author: Dinduks

cookbook/doctrine/reverse_engineering.rst

@@ -32,7 +32,7 @@ to a post record thanks to a foreign key constraint.
       `title` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
       `content` longtext COLLATE utf8_unicode_ci NOT NULL,
       `created_at` datetime NOT NULL,
-      PRIMARY KEY (`id`),
+      PRIMARY KEY (`id`)
     ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
 
     CREATE TABLE `blog_comment` (