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 new pouch 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.

[allencloud]

LGTM

[codecov-io]

Codecov Report

Merging #1432 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1432      +/-   ##
==========================================
- Coverage   38.75%   38.74%   -0.02%     
==========================================
  Files         250      250              
  Lines       16621    16621              
==========================================
- Hits         6441     6439       -2     
  Misses       9354     9354              
- Partials      826      828       +2

Impacted Files	Coverage Δ
ctrd/image.go	80.36% <0%> (-4.91%)	⬇️
daemon/mgr/container.go	49.35% <0%> (-0.26%)	⬇️
ctrd/container.go	48.06% <0%> (+0.77%)	⬆️
daemon/containerio/container_io.go	61.03% <0%> (+1.29%)	⬆️
main.go	60.13% <0%> (+2.09%)	⬆️
apis/server/utils.go	66.66% <0%> (+5.55%)	⬆️