Update plugin-crossorigin.zh-CN.md

[zhangshichuan]

这里应该是 [第三方] 而不是 [非三方] 吧

Checklist

• npm test passes
• tests are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

• any feature?
• close https://github.com/umijs/umi/ISSUE_URL

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View rendered docs/plugins/plugin-crossorigin.zh-CN.md

[codecov]

Codecov Report

Merging #5063 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5063   +/-   ##
=======================================
  Coverage   82.84%   82.84%           
=======================================
  Files         153      153           
  Lines        3381     3381           
  Branches      908      906    -2     
=======================================
  Hits         2801     2801           
- Misses        572      573    +1     
+ Partials        8        7    -1     

Impacted Files	Coverage Δ
packages/core/src/Config/Config.ts	61.78% <0.00%> (ø)

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