docs: clarify preserve runtime requirements

Author: fi3ework

website/docs/en/guide/solution/react.mdx

@@ -76,9 +76,15 @@ export default defineConfig({
 });
 ```
 
-When you need to keep native JSX in the build output, set the runtime to `'preserve'`. This mode retains JSX syntax so it can be processed later (for example by another bundler). Because the files stay unbundled, you must switch to bundleless mode by setting `bundle: false`.
+When you need to keep native JSX in the build output, set the runtime to `'preserve'`. This mode retains JSX syntax so it can be processed later (for example by another bundler).
 
-To emit `.jsx` files, configure the JS filename template while using the preserve runtime:
+::: warn
+
+Because the files stay unbundled, you must switch to bundleless mode by setting `bundle: false`.
+
+:::
+
+To emit `.jsx` files, configure the JS filename template through [output.filename](/config/rsbuild/output#outputfilename) while using the preserve runtime:
 
 ```ts title="rslib.config.ts" twoslash
 import { pluginReact } from '@rsbuild/plugin-react';

website/docs/zh/guide/solution/react.mdx

@@ -76,9 +76,15 @@ export default defineConfig({
 });
 ```
 
-当你希望在构建产物中保留原始 JSX 时，可以将 runtime 设置为 `'preserve'`。该模式会保留 JSX 语法，方便后续由其他打包工具处理。因为文件保持非打包状态，所以必须通过将 `bundle` 设为 `false` 启用 bundleless 模式。
+当你希望在构建产物中保留原始 JSX 时，可以将 runtime 设置为 `'preserve'`。该模式会保留 JSX 语法，方便后续由其他打包工具处理。
 
-若要输出 `.jsx` 后缀的文件，可在使用 preserve runtime 时配置 JS 文件名模版：
+::: warn
+
+因为文件保持非打包状态，所以必须通过将 `bundle` 设为 `false` 启用 bundleless 模式。
+
+:::
+
+若要输出 `.jsx` 后缀的文件，可通过 [output.filename](/config/rsbuild/output#outputfilename) 配置 JS 文件名模版：
 
 ```ts title="rslib.config.ts" twoslash
 import { pluginReact } from '@rsbuild/plugin-react';