signal.7: Fixes to the text of "Execution of signals handlers"

See https://lore.kernel.org/linux-man/3fac10ea-7fed-739b-4974-09845f34867f@gmail.com/

Reported-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
1 file changed