Merge "minor doc improvement for tombstone fd code" into main am: 1076e7f7

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2976171



Change-Id: I780a2f085005c7f603b086324b3354bdde21316e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>