bmc-reboot-cause: Update BMC reboot cause event log descriptions

Modify the design proposal to meet the current BMC reboot cause event
log mechanism

Change-Id: Ib35817c5c19b0011de3faff51fb42fe76b73176c
Signed-off-by: Patrick NC Lin <patrick.nc.lin.wiwynn@gmail.com>
diff --git a/designs/bmc-reboot-cause-update.md b/designs/bmc-reboot-cause-update.md
index da82f10..45571e8 100644
--- a/designs/bmc-reboot-cause-update.md
+++ b/designs/bmc-reboot-cause-update.md
@@ -61,9 +61,11 @@
 - Each BMC vendor must provide a driver to retrieve the BMC reboot cause and
   record the result at the specified location.
 
-2. Redefining Reboot Cause Type **WDIOF_EXTERN1**:
+2. Definition and Identification of Reboot Cause Type **Software Reset**:
 
-- This type will henceforth represent a software reset.
+- This one is still under discussion, please refer to the following link for
+  more detail:
+  https://lore.kernel.org/all/9565c496-44d8-4214-8038-931926210d0f@roeck-us.net/
 
 3. Revise the Definition of **WDIOF_CARDRESET**:
 
@@ -80,7 +82,6 @@
 
 | phosphor-state-manager | bootstatus value | watchdog driver                  |
 | ---------------------- | ---------------- | -------------------------------- |
-| WDIOF_EXTERN1          | 0x04             | return 0x04 if reset by Software |
 | WDIOF_CARDRESET        | 0x20             | return 0x20 if reset by Watchdog |
 | POR                    | 0x00             | Do nothing                       |