Use statement for InputOption added to example

Author: soxyl

console/input.rst

@@ -118,6 +118,9 @@ simply as a boolean flag without a value (e.g.  ``--yell``).
 For example, add a new option to the command that can be used to specify
 how many times in a row the message should be printed::
 
+    use Symfony\Component\Console\Input\InputOption;
+    // ...
+
     $this
         // ...
         ->addOption(