speakup: Document bleeps parameter values

speakup: Document bleeps parameter values

The speakup documentation had a TODO about accepted values for the
bleeps parameter. drivers/accessibility/speakup/main.c indicates
that it's a bitmasked param where bit 0 controls beeping and bit 1
controls announcements.

Signed-off-by: Henry Zhang <zeri@umich.edu>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://patch.msgid.link/20260128014501.1600263-1-zeri@umich.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>