update custom_vm.md with debian related contents am: eeccd6e328 am: f722c47199

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/3094123

Change-Id: I430edba92fd57d367864ce135f3c584c66f9e504
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>