docs: auto generate pouch cli/api docs via code

[pouchrobot]

Signed-off-by: pouchrobot pouch-dev@alibaba-inc.com

1.Describe what this PR did
This PR is automatically done by AI-based collaborating robot.
Pouchrobot will auto-generate cli/api document via https://github.com/spf13/cobra/tree/master/doc every day.

2.Does this pull request fix one issue?
None

3.Describe how you did it
First, execute command "make client" to build cli;
Second, execute command "./pouch gen-doc" to generate new cli docs.

For API part, we use a tool swagger2markup to make it.

4.Describe how to verify it
None

5.Special notes for reviews
The cli/api doc must be automatically generated.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request head (auto-doc-2018-12-13@1a387d2). Click here to learn what that means.
The diff coverage is n/a.

[ZYecho]

LGTM

[allencloud]

FILE: ./docs/features/pouch_with_criu.md
[✖] https://criu.org/Main_Page
[✖] https://criu.org/Linux_kernel
[✖] https://criu.org/Packages

ERROR: dead links found!

is unrelated. Merging...

LGTM