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 #2825 into master will decrease coverage by 7.09%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #2825     +/-   ##
=========================================
- Coverage   69.42%   62.33%   -7.1%     
=========================================
  Files         278      278             
  Lines       17444    17444             
=========================================
- Hits        12111    10874   -1237     
- Misses       3990     5300   +1310     
+ Partials     1343     1270     -73

Flag	Coverage Δ
#criv1alpha2_test	39.28% <ø> (-0.02%)	⬇️
#integration_test_0	36.53% <ø> (+0.02%)	⬆️
#integration_test_1	?
#integration_test_2	?
#integration_test_3	?
#node_e2e_test	35% <ø> (-0.07%)	⬇️
#unittest	28.75% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
ctrd/image_commit.go	0% <0%> (-69.29%)	⬇️
daemon/mgr/container_stats.go	6.21% <0%> (-61.59%)	⬇️
daemon/mgr/container_commit.go	0% <0%> (-56.1%)	⬇️
registry/auth.go	0% <0%> (-55.15%)	⬇️
daemon/mgr/image_save.go	0% <0%> (-50%)	⬇️
registry/auth_challenge.go	13.75% <0%> (-48.75%)	⬇️
storage/volume/modules/tmpfs/tmpfs.go	28.2% <0%> (-47.44%)	⬇️
daemon/mgr/image_load.go	0% <0%> (-41.18%)	⬇️
daemon/events/filter.go	60% <0%> (-40%)	⬇️
apis/server/system_bridge.go	9.67% <0%> (-39.79%)	⬇️
... and 53 more

[allencloud]

LGTM