Docker.raw docker文件清理

docker system df 
docker system prune

```bash
% du -h
 12K	./tasks
  0B	./plugins
 14M	./log/host
 17M	./log/vm
 32M	./log
  0B	./vms/0/log
9.4G	./vms/0/data
9.4G	./vms/0
9.4G	./vms
9.5G	.

data % ls
Docker.raw

 % docker system prune
WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all dangling images
  - all dangling build cache

Are you sure you want to continue? [y/N] y

% docker system df   
TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          6         0         1.179GB   1.179GB (100%)
Containers      0         0         0B        0B
Local Volumes   27        0         467.7MB   467.7MB (100%)
Build Cache     8         0         0B        0B

Data % du -h
 20K	./tasks
  0B	./plugins
 15M	./log/host
 18M	./log/vm
 33M	./log
  0B	./vms/0/log
4.2G	./vms/0/data
4.2G	./vms/0
4.2G	./vms
4.3G	.