minor #16869 [Console] Update questionhelper.rst (issamkhadiri1989)

This PR was submitted for the 6.0 branch but it was merged into the 5.4 branch instead.

Discussion
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[Console] 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.

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Commits
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cdcb931 Update questionhelper.rst

Author: javiereguiluz

components/console/helpers/questionhelper.rst

@@ -410,7 +410,7 @@ 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);