docs: remove all Gitee links

[chenjiahan]

Gitee 在没有通知的情况下，下线了所有 Gitee Pages 服务，参考这个 issue：https://gitee.com/oschina/git-osc/issues/I9L5FJ?from=project-issue

请访问 Vant 部署在 GitHub Pages 上的网站：

• Vant：https://vant-ui.github.io/vant/
• Vant Weapp：https://vant-ui.github.io/vant-weapp/

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.76%. Comparing base (80ca6fb) to head (38202fa).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12845      +/-   ##
==========================================
+ Coverage   89.73%   89.76%   +0.02%     
==========================================
  Files         257      257              
  Lines        6957     6957              
  Branches     1711     1711              
==========================================
+ Hits         6243     6245       +2     
  Misses        377      377              
+ Partials      337      335       -2     

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