docs(pro:search): add size description to documentation

[sallerli1]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

What is the new behavior?

补充高级搜索的 size 相关文档

Other information

[idux-bot]

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[codecov]

Codecov Report

Merging #1683 (0c57619) into main (8faddc1) will not change coverage.
The diff coverage is n/a.

❗ Current head 0c57619 differs from pull request most recent head 03794b6. Consider uploading reports for the commit 03794b6 to get more accurate results

@@           Coverage Diff           @@
##             main    #1683   +/-   ##
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  Coverage   92.54%   92.54%           
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  Files         345      345           
  Lines       32395    32395           
  Branches     3690     3690           
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  Hits        29981    29981           
  Misses       2414     2414