feat: add defaultValue for add operation

[kagawagao]

add defaultValue for add operation
#49

[vercel]

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[codecov]

Codecov Report

Merging #52 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #52   +/-   ##
=======================================
  Coverage   99.86%   99.86%           
=======================================
  Files          13       13           
  Lines         752      752           
  Branches      157      157           
=======================================
  Hits          751      751           
  Misses          1        1

Impacted Files	Coverage Δ
src/List.tsx	100% <100%> (ø)	⬆️

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[zombieJ]

ref ant-design/ant-design#20475