[Doc Link Fix No.46] 文档链接修复

[cvbret]

修复任务46的三处失效链接：

1. 补全Markdown链接语法；
2. 将占位符链接改为代码样式，避免404错误

[paddle-bot]

感谢你贡献飞桨文档，文档预览构建中，Docs-New 跑完后即可预览，预览链接：http://preview-pr-7779.paddle-docs-preview.paddlepaddle.org.cn/documentation/docs/zh/api/index_cn.html
预览工具的更多说明，请参考：飞桨文档预览工具

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
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[github-actions]

📚 本次 PR 文档预览链接（点击展开）

ℹ️ 预览提醒 请等待 Docs-NEW 流水线运行完成后再点击预览链接，否则可能会看到旧版本内容或遇到链接无法访问的情况。

• docs/dev_guides/docs_contributing_guides_cn.md: 点击预览

[Echo-Nie]

pls sign the CLA~