SUBMARINE-1303. Add Chinese website link

[cdmikechen]

What is this PR for?

Add locale dropdown for Chinese link https://submarine.apache.org/zh-cn/

What type of PR is it?

Documentation

Todos

• - Add locale dropdown

What is the Jira issue?

https://issues.apache.org/jira/browse/SUBMARINE-1303

How should this be tested?

No

Screenshots (if appropriate)

Questions:

• Do the license files need updating? No
• Are there breaking changes for older versions? No
• Does this need new documentation? No

[codecov]

Codecov Report

Merging #986 (ff579cc) into master (e4df974) will increase coverage by 5.08%.
The diff coverage is 67.50%.

@@             Coverage Diff              @@
##             master     #986      +/-   ##
============================================
+ Coverage      9.18%   14.26%   +5.08%     
- Complexity      670      991     +321     
============================================
  Files           234      241       +7     
  Lines         23716    23897     +181     
  Branches       3475     3473       -2     
============================================
+ Hits           2178     3410    +1232     
+ Misses        21407    20280    -1127     
- Partials        131      207      +76     

Impacted Files	Coverage Δ
...ine/server/api/exception/InvalidSpecException.java	100.00% <ø> (+100.00%)	⬆️
...ache/submarine/server/manager/NotebookManager.java	0.00% <ø> (ø)
...submitter/k8s/model/pytorchjob/PyTorchJobSpec.java	100.00% <ø> (+100.00%)	⬆️
...ne/server/submitter/k8s/model/tfjob/TFJobSpec.java	100.00% <ø> (+100.00%)	⬆️
...erver/submitter/k8s/parser/NotebookSpecParser.java	79.69% <ø> (+79.69%)	⬆️
...a/org/apache/submarine/server/SubmarineServer.java	62.28% <20.00%> (-1.25%)	⬇️
...submarine/server/submitter/k8s/model/AgentPod.java	87.09% <50.00%> (+87.09%)	⬆️
.../submarine/server/rest/workbench/LoginRestApi.java	60.00% <57.14%> (+60.00%)	⬆️
...e/submarine/server/submitter/k8s/K8sSubmitter.java	38.07% <59.25%> (+38.07%)	⬆️
...marine/server/submitter/k8s/model/tfjob/TFJob.java	65.71% <61.29%> (+65.71%)	⬆️
... and 70 more

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