NullOutput should be passed to $command->run()

as $command#execute() is protected, the NullOutput should be passed to $command#run() as that's the public method being invoked when calling an existing command.

Author: Ma27

components/console/introduction.rst

@@ -552,7 +552,7 @@ returns the returned code from the command (return value from command's
 
     If you want to suppress the output of the executed command, pass a
     :class:`Symfony\\Component\\Console\\Output\\NullOutput` as the second
-    argument to ``$command->execute()``.
+    argument to ``$command->run()``.
 
 .. caution::