lib/Kconfig.debug: document panic= command line option and procfs entry for PANIC_TIMEOUT

PANIC_TIMEOUT can also be controlled with the panic= kernel command line
option and the file /proc/sys/kernel/panic.  Let's document both of these
in the Kconfig help text.

Link: https://lkml.kernel.org/r/20240607152443.925168-1-bmasney@redhat.comSigned-off-by: Brian Masney <bmasney@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/Kconfig.debug

@@ -1043,7 +1043,9 @@ config PANIC_TIMEOUT
 	  Set the timeout value (in seconds) until a reboot occurs when
 	  the kernel panics. If n = 0, then we wait forever. A timeout
 	  value n > 0 will wait n seconds before rebooting, while a timeout
-	  value n < 0 will reboot immediately.
+	  value n < 0 will reboot immediately. This setting can be overridden
+	  with the kernel command line option panic=, and from userspace via
+	  /proc/sys/kernel/panic.
 
 config LOCKUP_DETECTOR
 	bool