Fixes typo.

reference/en/configuration.txt

@@ -9,7 +9,7 @@ You can get a DBAL Connection through the `Doctrine\DBAL\DriverManager` class.
         'dbname' => 'mydb',
         'user' => 'user',
         'password' => 'secret',
-        'host' => 'locahlost',
+        'host' => 'localhost',
         'driver' => 'pdo_mysql',
     );
     $conn = DriverManager::getConnection($connectionParams);