fix(element): fix vuepress doc not identify fetch

[muuyao]

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What have you changed?

fix vuepress doc not identify fetch

[codecov]

Codecov Report

Merging #1769 (39f971a) into formily_next (66fd1bc) will not change coverage.
The diff coverage is n/a.

@@              Coverage Diff              @@
##           formily_next    #1769   +/-   ##
=============================================
  Coverage         92.54%   92.54%           
=============================================
  Files               135      135           
  Lines              6013     6013           
  Branches           1495     1495           
=============================================
  Hits               5565     5565           
  Misses              444      444           
  Partials              4        4           

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