Add an example using the options in the help message

src/Symfony/Bundle/SwiftmailerBundle/Command/SendEmailCommand.php

@@ -37,6 +37,8 @@ class SendEmailCommand extends Command
             ->setHelp(<<<EOF
 The <info>swiftmailer:spool:send</info> command send all emails from the spool.
 
+<info>./app/console swiftmailer:spool:send --message-limit=10 --time-limit=10</info>
+
 EOF
             )
         ;