docs(browser): add usage of useInputFileSystem to "In-Memory File system" section (#11833)

* fix tag

* useInputFileSystem

Author: CPunisher

website/docs/en/api/javascript-api/browser.mdx

@@ -81,6 +81,28 @@ builtinMemFs.volume.fromJSON({
 const files = builtinMemFs.volume.toJSON();
 ```
 
+`builtinMemFs` is a global singleton instance. In scenarios involving concurrent builds of multiple projects, it is recommended to enable [experiments.useInputFileSystem](/config/experiments#experimentsuseinputfilesystem) to avoid conflicts.  
+Please note that, currently in the `@rspack/browser`, `experiments.useInputFileSystem` can only intercept project files that will be ultimately bundled, and cannot intercept files relied upon during the build process, such as those used by Loaders (see also [BrowserRequirePlugin#modules](/api/javascript-api/browser#modules) below).
+
+```js title="rspack.config.mjs"
+const projectFs = memfs(filteredFiles);
+export default {
+  plugins: [
+    {
+      apply: compiler => {
+        compiler.hooks.beforeCompile.tap('SimpleInputFileSystem', () => {
+          compiler.inputFileSystem = projectFs;
+          compiler.outputFileSystem = projectFs;
+        });
+      },
+    },
+  ],
+  experiments: {
+    useInputFileSystem: [/.*/],
+  },
+};
+```
+
 ## Browser-Specific Plugins
 
 To better meet the bundling needs in browser environments, `@rspack/browser` offers several dedicated plugins.
@@ -147,9 +169,7 @@ interface BrowserHttpImportPluginOptions {
 
 In Rspack, certain scenarios require dynamically loading and executing JavaScript code, such as [Loaders](/guide/features/loader) or the template functions of [HtmlRspackPlugin](/plugins/rspack/html-rspack-plugin#use-template-function). Since this code may come from untrusted users, executing it directly in the browser environment poses potential security risks. To ensure safety, `@rspack/browser` throws errors by default in such cases to prevent unsafe code execution.
 
-The `BrowserRequirePlugin` plugin provides two ways to address this requirement.
-
-Options for `BrowserRequirePlugin` are as follows:
+The `BrowserRequirePlugin` plugin provides two ways to address this requirement. Options for `BrowserRequirePlugin` are as follows:
 
 ```ts
 interface BrowserRequirePluginOptions {
@@ -167,7 +187,7 @@ interface BrowserRequirePluginOptions {
 
 #### `modules`
 
-<ApiMeta addedVersion="1.5.9" />
+<ApiMeta addedVersion="1.6.0-beta.0" />
 
 This option allows you to directly map a module request id to any JavaScript object within the project. Note that you need to create a corresponding empty file in `memfs`:
 

website/docs/zh/api/javascript-api/browser.mdx

@@ -82,6 +82,28 @@ builtinMemFs.volume.fromJSON({
 const files = builtinMemFs.volume.toJSON();
 ```
 
+`builtinMemFs` 是一个全局单例实例。在存在并发构建多个项目的场景下，建议启用 [experiments.useInputFileSystem](/config/experiments#experimentsuseinputfilesystem) 以避免冲突。  
+需要注意的是，目前在 `@rspack/browser` 环境中，`experiments.useInputFileSystem` 仅能拦截最终将被打包的项目文件，无法拦截诸如 Loader 等构建过程中依赖的文件（见下文 [BrowserRequirePlugin#modules](/api/javascript-api/browser#modules)）。
+
+```js title="rspack.config.mjs"
+const projectFs = memfs(filteredFiles);
+export default {
+  plugins: [
+    {
+      apply: compiler => {
+        compiler.hooks.beforeCompile.tap('SimpleInputFileSystem', () => {
+          compiler.inputFileSystem = projectFs;
+          compiler.outputFileSystem = projectFs;
+        });
+      },
+    },
+  ],
+  experiments: {
+    useInputFileSystem: [/.*/],
+  },
+};
+```
+
 ## 浏览器专用插件
 
 为更好地满足浏览器环境下的打包需求，`@rspack/browser` 提供了若干专用插件。
@@ -145,9 +167,7 @@ interface BrowserHttpImportPluginOptions {
 
 在 Rspack 中，某些场景需要动态加载和执行 JavaScript 代码，如 [Loader](/guide/features/loader) 或 [HtmlRspackPlugin 的模板函数](/plugins/rspack/html-rspack-plugin#use-template-function)。由于这些代码可能来自不可信的第三方用户，直接在浏览器环境中执行会带来潜在的安全风险。为了保障安全性，`@rspack/browser` 在遇到此类场景时会默认抛出错误，阻止不安全代码的执行。
 
-`BrowserRequirePlugin` 插件提供了两种方式解决这个需求。
-
-`BrowserRequirePlugin` 的选项如下：
+`BrowserRequirePlugin` 插件提供了两种方式解决这个需求。`BrowserRequirePlugin` 的选项如下：
 
 ```ts
 /**
@@ -174,7 +194,7 @@ interface BrowserRequirePluginOptions {
 
 #### `modules`
 
-<ApiMeta addedVersion="1.5.9" />
+<ApiMeta addedVersion="1.6.0-beta.0" />
 
 该选项能够直接将模块请求 id 映射到项目内的任意 JavaScript 对象，注意，这里需要在 memfs 中对应地写入一个空的文件：