Update math.py

[zrz0359]

cauchy_

Description

更新了cauchy_的中文文档

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[SigureMo]

1. cauchy_ 在 python/paddle/tensor/creation.py 而不是这里
2. PR 描述说是更新中文文档，但中文文档在 docs repo 而不是这里
3. 动机是什么？修复了什么？如果最初动机是 【Docathon】补充缺失的中文 API 文档（Inplace 类） docs#7090，请在 PR 描述里说清楚，并链接过去，同时要说明具体修改了什么，为什么要修改