Update questionhelper.rst

hello

the example shows a warning (preg_match(): No ending delimiter'/' found). to solve it, we need to add the ``/`` at the end of the regex.

Author: issamkhadiri1989

components/console/helpers/questionhelper.rst

@@ -401,7 +401,7 @@ invalid answer and will only be able to proceed if their input is valid.
 
         $question = new Question('Please enter the name of the bundle', 'AcmeDemoBundle');
         $validation = Validation::createCallable(new Regex([
-            'pattern' => '/^[a-zA-Z]+Bundle$',
+            'pattern' => '/^[a-zA-Z]+Bundle$/',
             'message' => 'The name of the bundle should be suffixed with \'Bundle\'',
         ]));
         $question->setValidator($validation);