Update ART Service doc. am: f6886c25e0

Original change: https://android-review.googlesource.com/c/platform/art/+/2612931

Change-Id: Iec2c7c745498a62e36c56834af33ad7810aa4752
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>