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.

[codecov-io]

Codecov Report

Merging #1420 into master will increase coverage by 1.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1420      +/-   ##
==========================================
+ Coverage   37.68%   38.77%   +1.09%     
==========================================
  Files         174      250      +76     
  Lines       13871    16630    +2759     
==========================================
+ Hits         5227     6449    +1222     
- Misses       7822     9355    +1533     
- Partials      822      826       +4

Impacted Files	Coverage Δ
daemon/mgr/container.go	49.44% <0%> (-0.18%)	⬇️
cli/ulimit.go	0% <0%> (ø)
cli/logs.go	0% <0%> (ø)
client/request.go	58.53% <0%> (ø)
client/image_inspect.go	100% <0%> (ø)
cli/blkio.go	69.66% <0%> (ø)
client/utils.go	75% <0%> (ø)
cli/upgrade.go	0% <0%> (ø)
cli/restart.go	0% <0%> (ø)
client/container_get.go	100% <0%> (ø)
... and 110 more

[allencloud]

LGTM