docs: auto generate pouch cli/api docs via code

[pouchrobot]

Signed-off-by: pouchrobot [email protected]

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.

[codecov-io]

Codecov Report

Merging #1544 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1544      +/-   ##
==========================================
+ Coverage   40.67%   40.72%   +0.04%     
==========================================
  Files         254      254              
  Lines       16635    16635              
==========================================
+ Hits         6767     6775       +8     
+ Misses       9001     8994       -7     
+ Partials      867      866       -1

Impacted Files	Coverage Δ
ctrd/image.go	79.42% <0%> (+1.71%)	⬆️
daemon/containerio/container_io.go	61.53% <0%> (+3.2%)	⬆️

[allencloud]

LGTM