Usage documentation for 'procd_send_signal' states "The signal is SIGHUP
by default, and must be specified by NAME." Make actual behaviour match
the stated documented behaviour.
https://wiki.openwrt.org/inbox/procd-init-scripts
Suggested-by: Jo-Philip Wich <jow@mein.io>
Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>