chore: add translation guide into contributing.md

[Jinjiang]

Ref: #1770 (reply in thread)

Thanks.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.37%. Comparing base (1a3a28f) to head (9602b2c).
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@@            Coverage Diff             @@
##             main    #1778      +/-   ##
==========================================
- Coverage   90.86%   90.37%   -0.49%     
==========================================
  Files          24       24              
  Lines        1116     1195      +79     
  Branches      347      378      +31     
==========================================
+ Hits         1014     1080      +66     
- Misses         63       70       +7     
- Partials       39       45       +6     

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[posva]

I think we should add a link to the translation folder here as other translations might be hosted in a different repository. This will make more sense after adding an external translation

[posva]

Looks good to me! Thanks a lot!

[Jinjiang]

@posva I missed the link to the zh folder. Here it is.