uwb(hal): Doc update to clarify country code payload of 00 am: 778ddca7

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/interfaces/+/19698276



Change-Id: I9b86749776f49fe09c2934ec2e3a63eca7123d6f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>