docs: add atomic migration instructions for v6 installation (#55958)

* docs: add atomic migration instructions for v6 installation

* Update docs/react/migration-v6.zh-CN.md

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* Update docs/react/migration-v6.en-US.md

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Signed-off-by: 遇见同学 <1875694521@qq.com>

---------

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

docs/react/migration-v6.en-US.md

@@ -372,6 +372,10 @@ In v5, Form.List was treated as a single Field, causing `onFinish` to include al
 - CSS variables are enabled by default and only modern browsers are supported.
 - IE is no longer supported. Some older domestic browsers may have compatibility issues — please verify target browsers before shipping your app.
 
+### Atomic Migration: Install v6 via Package Alias
+
+- If you need to limit the migration's impact, you can try an [atomic migration](https://github.com/ant-design/ant-design/discussions/55957). Please note that this is not the recommended upgrade path.
+
 ## Upgrade checklist
 
 To ensure your app works correctly after upgrading to v6, please go through the following checklist:

docs/react/migration-v6.zh-CN.md

@@ -368,6 +368,10 @@ v5 版本中，Form.List 会被认为是一个 Field，以至于提交时会包
 - 默认开启 **CSS variables**，仅支持现代浏览器。
 - IE 浏览器不再支持，部分旧版国产浏览器可能存在兼容性问题，请在应用发布前确认目标浏览器的支持情况。
 
+### 原子级通过别名安装 v6
+
+- 如果你需要控制升级的影响范围，可以尝试[原子级迁移](https://github.com/ant-design/ant-design/discussions/55957)方案。请注意，这并非我们推荐的升级路径。
+
 ## 升级影响排查 Checklist
 
 为了确保升级到 v6 后项目正常运行，请参考以下检查清单逐项确认：