docs(zh): Sync Chinese translation (#5051) [ci skip]

docs/zh/guide/css.md

@@ -100,8 +100,13 @@ module.exports = {
   css: {
     loaderOptions: {
       css: {
-        localIdentName: '[name]-[hash]',
-        camelCase: 'only'
+        // 注意：以下配置在 Vue CLI v4 与 v3 之间存在差异。
+        // Vue CLI v3 用户可参考 css-loader v1 文档
+        // https://github.com/webpack-contrib/css-loader/tree/v1.0.1
+        modules: {
+          localIdentName: '[name]-[hash]'
+        },
+        localsConvention: 'camelCaseOnly'
       }
     }
   }