update_kernel.sh: Do not suggest --ignore-verity option

It's usually a bad idea, especially for new team members who
actually read the warning in full.

--ignore-verity may have some rare use cases though (e.g. when
debugging verity itself), so we keep it, but we also add a
warning in the help file.

TEST=./update_kernel.sh --help

Change-Id: I64a7c76281d4752d9600b786ca1568930f635773
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2488828
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Commit-Queue: Douglas Anderson <dianders@chromium.org>
diff --git a/update_kernel.sh b/update_kernel.sh
index 113aac5..03243a9 100755
--- a/update_kernel.sh
+++ b/update_kernel.sh
@@ -21,7 +21,8 @@
 DEFINE_string arch "" "Override architecture reported by target"
 DEFINE_boolean clean $FLAGS_FALSE "Remove old files before sending new files"
 DEFINE_boolean hv $FLAGS_TRUE "Use hypervisor kernel if available."
-DEFINE_boolean ignore_verity $FLAGS_FALSE "Update kernel even if system is using verity"
+DEFINE_boolean ignore_verity $FLAGS_FALSE "Update kernel even if system is using verity \
+(WARNING: likely to make the system unable to boot)"
 DEFINE_boolean reboot $FLAGS_TRUE "Reboot system after update"
 DEFINE_boolean vboot $FLAGS_TRUE "Update the vboot kernel"
 DEFINE_boolean syslinux $FLAGS_TRUE "Update the syslinux kernel (including /boot)"
@@ -81,7 +82,7 @@
         warn "System is using verity: First remove rootfs verification using"
         warn "/usr/share/vboot/bin/make_dev_ssd.sh --remove_rootfs_verification"
-        warn "on the DUT, or add --ignore_verity parameter to this command."
+        warn "on the DUT."