docs(Form): fix variable errors

[pany-ang]

修复该 issue: #13493

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.67%. Comparing base (ec5b45b) to head (7f8dd23).
Report is 115 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13499      +/-   ##
==========================================
+ Coverage   89.60%   89.67%   +0.07%     
==========================================
  Files         257      257              
  Lines        7013     7033      +20     
  Branches     1736     1741       +5     
==========================================
+ Hits         6284     6307      +23     
+ Misses        384      383       -1     
+ Partials      345      343       -2     

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[chenjiahan]

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