[Console] added a Shell

src/Symfony/Components/Console/Shell.php

@@ -139,7 +139,7 @@ Welcome to the <info>{$this->application->getName()}</info> shell.
 At the prompt, type <comment>help</comment> for some help,
 or <comment>list</comment> to get a list available commands.
 
-To exit the shell, type <comment>^D</comment>.
+To exist the shell, type <comment>^D</comment>.
 
 EOF;
   }