[Console] added ? as an alias for the help command

src/Symfony/Components/Console/Command/HelpCommand.php

@@ -42,6 +42,7 @@ class HelpCommand extends Command
         new InputOption('xml', null, InputOption::PARAMETER_NONE, 'To output help as XML'),
       ))
       ->setName('help')
+      ->setAliases(array('?'))
       ->setDescription('Displays help for a command')
       ->setHelp(<<<EOF
 The <info>help</info> command displays help for a given command: