[FrameworkBundle] Add --show-arguments example to debug:container command help text

Author: jschaedl

Command/ContainerDebugCommand.php

@@ -74,6 +74,10 @@ protected function configure()
 
   <info>php %command.full_name% validator</info>
 
+To get specific information about a service including all its arguments, use the <info>--show-arguments</info> flag:
+
+  <info>php %command.full_name% validator --show-arguments</info>
+
 To see available types that can be used for autowiring, use the <info>--types</info> flag:
 
   <info>php %command.full_name% --types</info>