Serial HOWTO is maintained by it's author directly. You can let a comment on the discussion page, but you have no evidence it will be seen by the author. Evntually contact the author directly.
Discussion Page Content
SERIAL-HOWTO
Serial HOWTO is maintained by it's author directly and is available here:
PDF to be able to read it you need Adobe reader. Adobe reader is free as free beer, but not as free speech.