minor #8111 QuestionHelper - disableStty is static method (SpacePossum)

This PR was merged into the 3.3 branch.

Discussion
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QuestionHelper - `disableStty` is static method

The docs suggest disabling stty must be done on each instance of `QuestionHelper`, however it is a static method setting a static property, i.e. it effects _all_ instances.
Besides, its always a good idea to call `static` methods using the `static` call syntax.

Commits
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c48d595 Update questionhelper.rst

Author: xabbuh

components/console/helpers/questionhelper.rst

@@ -212,14 +212,15 @@ convenient for passwords::
     On Windows systems, this ``stty`` command may generate gibberish output and
     mangle the input text. If that's your case, disable it with this command::
 
+        use Symfony\Component\Console\Helper\QuestionHelper;
         use Symfony\Component\Console\Question\ChoiceQuestion;
 
         // ...
         public function execute(InputInterface $input, OutputInterface $output)
         {
             // ...
             $helper = $this->getHelper('question');
-            $helper->disableStty();
+            QuestionHelper::disableStty();
 
             // ...
         }