docs: improve lintOnSave docs [ci skip]

Author: yyx990803

docs/config/README.md

@@ -135,9 +135,13 @@ module.exports = {
 - Type: `boolean | 'error'`
 - Default: `true`
 
+  ::: tip
+  If you want lint errors to show up in the browser overlay, set this to `'error'`.
+  :::
+
   Whether to perform lint-on-save during development using [eslint-loader](https://github.com/webpack-contrib/eslint-loader). This value is respected only when [`@vue/cli-plugin-eslint`](https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-eslint) is installed.
 
-  When set to `true`, eslint-loader will only emit warnings during webpack's compilation process in order not to break the flow during development. If you want it to emit errors instead (i.e. when building for production), set it like this: `lintOnSave: 'error'`.
+  When set to `true`, eslint-loader will emit warnings (which only get logged to the terminal to avoid interrupting development). If you want it to emit errors instead, set it to `'error'`. This will make lint errors show up in the in-browser dev overlay and will make your build fail on lint errors.
 
 ### runtimeCompiler
 

docs/zh/config/README.md

@@ -133,9 +133,13 @@ module.exports = {
 - Type: `boolean` | `'error'`
 - Default: `true`
 
+  ::: tip
+  如果你想要让 lint 错误在开发时直接显示在浏览器中，将这个选项设置为 `'error'`。
+  :::
+
   是否在开发环境下通过 [eslint-loader](https://github.com/webpack-contrib/eslint-loader) 在每次保存时 lint 代码。这个值会在 [`@vue/cli-plugin-eslint`](https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-eslint) 被安装之后生效。
 
-  设置为 `true` 时，eslint-loader 在 webpack 的编译过程中只会触发警告，以避免中断开发流程。如果你希望换做触发错误 (例如在为生成环境构建时)，可以这样设置：`lintOnSave: 'error'`。
+  设置为 `true` 时，eslint-loader 在 webpack 的编译过程中会触发输出到控制台的警告，以避免中断开发流程。如果设置为 `'error'`，则 lint 错误会在开发时直接显示在浏览器中。另外构建时如果存在 lint 错误会导致构建失败。
 
 ### runtimeCompiler