docs: fix stop example

[ZYecho]

Signed-off-by: zhangyue [email protected]

Ⅰ. Describe what this PR did

pouch stop -h, example looks not correct.

 Examples:
$ pouch ps
Name     ID       Status    Image                              Runtime
foo      71b9c1   Running   docker.io/library/busybox:latest   runc
$ pouch stop foo
$ pouch ps
Name     ID       Status    Image                              Runtime
foo      71b9c1   Stopped   docker.io/library/busybox:latest   runc

pouch ps doesn't list containers in STOP state. must use -a flag.

Ⅱ. Does this pull request fix one issue?

None

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

Yes

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[pouchrobot]

We found this is your first time to contribute to Pouch, @ZYecho
👏 We really appreciate it.
Just remind that you have read the contribution guide: https://github.com/alibaba/pouch/blob/master/CONTRIBUTING.md
If you didn't, you should do that first. If done, welcome again and please enjoy hacking! 🍻

[allencloud]

Good catch. The removal of -a is reasonable. Thanks a lot. @ZYecho
LGTM