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

Merging #2604 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2604      +/-   ##
==========================================
- Coverage   69.46%   69.45%   -0.02%     
==========================================
  Files         279      279              
  Lines       18825    18825              
==========================================
- Hits        13077    13074       -3     
- Misses       4281     4282       +1     
- Partials     1467     1469       +2

Flag	Coverage Δ
#criv1alpha1test	31.85% <ø> (-0.02%)	⬇️
#criv1alpha2test	36.1% <ø> (-0.12%)	⬇️
#integrationtest	41.14% <ø> (-0.02%)	⬇️
#nodee2etest	33.19% <ø> (-0.06%)	⬇️
#unittest	26.78% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
cri/v1alpha2/cri_wrapper.go	65.59% <0%> (-1.21%)	⬇️
cri/v1alpha2/cri.go	68.81% <0%> (-0.5%)	⬇️
daemon/mgr/container.go	59% <0%> (+0.21%)	⬆️
cri/v1alpha1/cri.go	60.92% <0%> (+0.33%)	⬆️

[allencloud]

LGTM