bug #3998 [Console] Fixed QuestionHelper examples (florianv)

This PR was merged into the 2.5 branch.

Discussion
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[Console] Fixed QuestionHelper examples

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.5+
| Fixed tickets |

The default value corresponds to the index of the choice in the array, not it's name.

Commits
-------

97c3894 [Console] Fixed QuestionHelper examples

components/console/helpers/questionhelper.rst

@@ -77,7 +77,7 @@ from a predefined list::
     $question = new ChoiceQuestion(
         'Please select your favorite color (defaults to red)',
         array('red', 'blue', 'yellow'),
-        'red'
+        0
     );
     $question->setErrorMessage('Color %s is invalid.');
 
@@ -109,9 +109,9 @@ this use :method:`Symfony\\Component\\Console\\Question\\ChoiceQuestion::setMult
 
     $helper = $this->getHelper('question');
     $question = new ChoiceQuestion(
-        'Please select your favorite color (defaults to red)',
+        'Please select your favorite colors (defaults to red and blue)',
         array('red', 'blue', 'yellow'),
-        'red'
+        '0,1'
     );
     $question->setMultiselect(true);
 
@@ -121,6 +121,9 @@ this use :method:`Symfony\\Component\\Console\\Question\\ChoiceQuestion::setMult
 Now, when the user enters ``1,2``, the result will be:
 ``You have just selected: blue, yellow``.
 
+If the user does not enter anything, the result will be:
+``You have just selected: red, blue``.
+
 Autocompletion
 ~~~~~~~~~~~~~~