docs(usage): update contents

demo/pages/docs/usage/enUS/index.md

@@ -1,16 +1,40 @@
 <!--anchor:on-->
 
+<!--anchor:on-->
+
 # Usage
 
 ## Quick Start
 
-Add the following lines in you entry point js file.
+### Import Directly
+
+Import component and use it.
+
+```html
+<template>
+  <n-button>naive-ui</n-button>
+</template>
+
+<script>
+  import { NButton } from 'naive-ui'
+
+  export default {
+    components: {
+      NButton
+    }
+  }
+</script>
+```
+
+### Install Entire UI Globally (not Recommended)
+
+No tree-shaking. Bundle will have redundant codes.
 
 ```js
 import { createApp } from 'vue'
 import naive from 'naive-ui'
 
-const app = createApp()
+const app = createApp(App)
 app.use(naive)
 ```
 
@@ -34,27 +58,34 @@ app.use(naive)
 
 ## Import on Demand (Tree Shaking)
 
-naive-ui support tree shaking, you can directly import components or install ui globally.
+Naive-ui support tree shaking for components, locales and themes.
 
-### Use Components Directly
+By default the component theme is light, locale is enUS, no extra imports is needed.
+
+For more info about theming, see [Customize Theme](customize-theme).
 
 ```html
-<template>
-  <n-button>naive-ui</n-button>
-</template>
-
 <script>
-  import { NButton } from 'naive-ui'
+  import { NConfigProvider, NButton, NDatePicker } from 'naive-ui'
+  // theme
+  import { createTheme, buttonDark, datePickerDark } from 'naive-ui'
+  // locale & dateLocale
+  import { zhCN, dateZhCN } from 'naive-ui'
 
-  export default {
-    components: {
-      NButton
-    }
-  }
+  ...
 </script>
+
+<template>
+  <n-config-provider :theme="darkTheme" :locale="zhCN" :date-locale="enUS">
+    <n-button>naive-ui</n-button>
+    <n-date-picker />
+  </n-config-provider>
+</template>
 ```
 
-### Install Globally
+### Install Globally (Not Recommended)
+
+It is not friendly with types.
 
 ```js
 import { createApp } from 'vue'
@@ -70,6 +101,5 @@ const naive = create({
 })
 
 const app = createApp()
-
 app.use(naive)
 ```

demo/pages/docs/usage/zhCN/index.md

@@ -4,13 +4,35 @@
 
 ## 快速开始
 
-在你项目的 javascript 入口文件添加下列代码。
+### 直接引入
+
+直接引入组件并使用
+
+```html
+<template>
+  <n-button>naive-ui</n-button>
+</template>
+
+<script>
+  import { NButton } from 'naive-ui'
+
+  export default {
+    components: {
+      NButton
+    }
+  }
+</script>
+```
+
+### 全量引入（不推荐）
+
+失去 tree-shaking 的能力，打包有冗余代码。
 
 ```js
 import { createApp } from 'vue'
 import naive from 'naive-ui'
 
-const app = createApp()
+const app = createApp(App)
 app.use(naive)
 ```
 
@@ -33,28 +55,35 @@ app.use(naive)
 
 ## 按需引入（Tree Shaking）
 
-naive-ui 支持 tree shaking，你可以使用直接引入或全局安装的方式的方式。
+naive-ui 支持 tree shaking，组件、语言、主题均可 tree-shaking。
 
-### 直接引入
+默认情况组件主题为亮色，语言为英文，无需额外导入。
+
+了解更多关于主题设定的信息，参见[调整主题](customize-theme)。
 
 ```html
-<template>
-  <n-button>naive-ui</n-button>
-</template>
-
 <script>
-  import { NButton } from 'naive-ui'
+  import { NConfigProvider, NButton, NDatePicker } from 'naive-ui'
+  // theme
+  import { createTheme, buttonDark, datePickerDark } from 'naive-ui'
+  // locale & dateLocale
+  import { zhCN, dateZhCN } from 'naive-ui'
 
-  export default {
-    components: {
-      NButton
-    }
-  }
+  ...
 </script>
+
+<template>
+  <n-config-provider :theme="darkTheme" :locale="zhCN" :date-locale="enUS">
+    <n-button>naive-ui</n-button>
+    <n-date-picker />
+  </n-config-provider>
+</template>
 ```
 
 ### 全局安装
 
+不推荐，对类型提示不友好
+
 ```js
 import { createApp } from 'vue'
 import {