doc/mb/ocp: Update DeltaLake for VPD variables used in LinuxBoot

u-root commits:
bmc_bootorder_override
https://github.com/u-root/u-root/pull/1902
systemboot_log_level:
https://github.com/u-root/u-root/pull/1922

Change-Id: I3da7291188ee06c50008aa3fc7142210215044d4
Signed-off-by: Johnny Lin <johnny_lin@wiwynn.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50377
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marc Jones <marc@marcjonesconsulting.com>
diff --git a/Documentation/mainboard/ocp/deltalake.md b/Documentation/mainboard/ocp/deltalake.md
index 9ef2357..017386e 100644
--- a/Documentation/mainboard/ocp/deltalake.md
+++ b/Documentation/mainboard/ocp/deltalake.md
@@ -58,6 +58,11 @@
 VPD variables supported are:
 - firmware_version: This variable holds overall firmware version. coreboot
   uses that value to populate smbios type 1 version field.
+- bmc_bootorder_override: When it's set to 1 IPMI OEM command can override boot
+  order. The boot order override is done in the u-root LinuxBoot payload.
+- systemboot_log_level: u-root package systemboot log levels, would be mapped to
+  quiet/verbose in systemboot as that is all we have for now. 5 to 8 would be mapped
+  to verbose, 0 to 4 and 9 would be mapped to quiet.
 - DeltaLake specific VPDs: check mb/ocp/deltalake/vpd.h.
 
 ## Working features