Automatic merge from submit-queue

Doc referrence "container-id" incorrect

File "docs\proposals\disk-accounting.md", line 154, "Everything under  `/var/lib/docker/overlay/<container-id>` are files required for running the container", here "container-id" is incorrect because files under "/var/lib/docker/overlay" are layer files, and  "container-id"  should be "id" thus consistent with line 148 "Image layers and writable layers are stored under `/var/lib/docker/overlay/<id>`".