docs: add default module definition systems

Author: Timeless0911

website/docs/en/config/lib/format.mdx

@@ -13,3 +13,32 @@ See [Output Format](/guide/basic/output-format) and [Module Federation](/guide/a
 The `umd` format only works when [bundle](/config/lib/bundle) is set to `true`.
 
 :::
+
+## Module definition systems
+
+In different output formats, Rslib uses the following default module definition systems:
+
+- `esm`：[modern-module](https://rspack.dev/config/output#type-modern-module)
+- `cjs`：[commonjs-static](https://rspack.dev/config/output#type-commonjs-static)
+- `umd`：[umd](https://rspack.dev/config/output#type-umd)
+
+If you want to use a different module definition system, you can configure the [tools.rspack.output.library.type](https://rspack.dev/config/output#outputlibrarytype) option. Below is an example that sets the module definition system for the `cjs` format to `commonjs`:
+
+```ts title="rslib.config.ts"
+export default {
+  lib: [
+    {
+      format: 'cjs',
+      tools: {
+        rspack: {
+          output: {
+            library: {
+              type: 'commonjs',
+            },
+          },
+        },
+      },
+    },
+  ],
+};
+```

website/docs/zh/config/lib/format.mdx

@@ -11,3 +11,32 @@
 ::: note
 `umd` 格式仅在 [bundle](/config/lib/bundle) 设置为 `true` 时有效。
 :::
+
+## 模块定义系统
+
+在不同的产物格式下，Rslib 默认使用的模块定义系统如下：
+
+- `esm`：[modern-module](https://rspack.dev/zh/config/output#type-modern-module)
+- `cjs`：[commonjs-static](https://rspack.dev/zh/config/output#type-commonjs-static)
+- `umd`：[umd](https://rspack.dev/zh/config/output#type-umd)
+
+如果你想要使用其他的模块定义系统，可以配置 [tools.rspack.output.library.type](https://rspack.dev/zh/config/output#outputlibrarytype) 选项。以下是一个示例，将 `cjs` 产物的模块定义系统设置为 `commonjs`：
+
+```ts title="rslib.config.ts"
+export default {
+  lib: [
+    {
+      format: 'cjs',
+      tools: {
+        rspack: {
+          output: {
+            library: {
+              type: 'commonjs',
+            },
+          },
+        },
+      },
+    },
+  ],
+};
+```