docs: add Rspack config validation to migration guide (#3309)

website/docs/en/guide/migration/rsbuild-0-x.mdx

@@ -92,6 +92,15 @@ export default {
 };
 ```
 
+## [Important] Rspack Config Validation
+
+Rsbuild now enables Rspack's scheme validation by default to ensure the Rspack configuration is correct.
+
+- If there is a type error in the Rspack config object, an error will be thrown and the build will be aborted.
+- If there are extra fields in the Rspack config object, an error will be thrown, but the build will not fail.
+
+> For more details, see [Rspack - RSPACK_CONFIG_VALIDATE](https://rspack.dev/guide/migration/webpack#updating-configuration).
+
 ## source.alias
 
 Removed `target` param for `source.alias` function, use [environments](/config/environments) config instead.

website/docs/zh/guide/migration/rsbuild-0-x.mdx

@@ -92,6 +92,15 @@ export default {
 };
 ```
 
+## [重要] Rspack 配置校验
+
+Rsbuild 现在默认启用 Rspack 的 scheme 校验，以确保 Rspack 配置的正确性。
+
+- 当 Rspack 配置的类型错误时，会抛出错误并终止构建。
+- 当 Rspack 配置中存在多余的字段时，会抛出错误，但不会终止构建。
+
+> 详见 [Rspack - RSPACK_CONFIG_VALIDATE](https://rspack.dev/guide/migration/webpack#updating-configuration)。
+
 ## source.alias
 
 移除 `source.alias` 函数的 `target` 参数，改用 [environments](/config/environments) 配置。
@@ -334,7 +343,8 @@ export default {
 
 ```diff
 export default {
-  dev: {
+-  dev: {
++  server: {
 -   startUrl: true,
 +   open: true,
   }