📝 Fill up doc with delegate support description.

Author: AlexV525

README-ZH.md

@@ -33,6 +33,7 @@ Language: [English](README.md) | 中文简体
   * [完整参数的使用方法](#完整参数的使用方法)
   * [展示选中的资源](#展示选中的资源)
   * [注册资源变化回调](#注册资源变化回调)
+  * [自定义类型或 UI](#自定义类型或-ui)
 * [类介绍](#类介绍-)
   * [`AssetEntity`](#assetentity)
 * [常见问题](#常见问题-)
@@ -48,9 +49,10 @@ Language: [English](README.md) | 中文简体
 
 ## 特性 ✨
 
-- [x] 💚 99%的微信风格
+- [x] ♻️ 支持基于代理重载的全量自定义
+- [x] 💚 99% 的微信风格
 - [x] 📷 图片资源支持
-  - [x] 🔬HEIC格式图片支持
+  - [x] 🔬HEIC 格式图片支持
 - [x] 🎥 视频资源支持
 - [x] 🎶 音频资源支持
 - [x] 1️⃣ 单资源模式
@@ -193,13 +195,21 @@ Image(image: AssetEntityImageProvider(asset, isOriginal: false))
 请查看示例以了解它如何进行展示。
 
 ### 注册资源变化回调
+
 ```dart
 AssetPicker.registerObserve(); // 注册回调
 ```
 ```dart
 AssetPicker.unregisterObserve(); // 取消注册回调
 ```
 
+### Customize with your own type or UI
+
+`AssetPickerBuilderDelegate`、`AssetPickerViewerBuilderDelegate`、`AssetPickerProvider` 及
+`AssetPickerViewerProvider` 均已暴露且可重载。使用者可以使用自定义的泛型类型 <A: 资源, P: 路径>，配合继承与
+重载，实现对应抽象类和类中的方法。更多用法请查看示例中的 `Custom` 页面，该页面实现了以 <File, Directory> 为
+类型基础的选择器。
+
 ## 类介绍 💭
 
 ### `AssetEntity`

README.md

@@ -54,6 +54,7 @@ This project follows the [all-contributors](https://github.com/all-contributors/
   * [Complete param usage](#complete-param-usage)
   * [Display selected assets](#display-selected-assets)
   * [Register assets change observe callback](#register-assets-change-observe-callback)
+  * [Customize with your own type or UI](#customize-with-your-own-type-or-ui)
 * [Classes Introduction](#classes-introduction-)
   * [`AssetEntity`](#assetentity)
 * [Frequent asked question](#frequent-asked-question-)
@@ -69,6 +70,7 @@ See [Migration Guide](doc/migration_guide.md).
 
 ## Features ✨
 
+- [x] ♻️ Fully implementable with delegate override.
 - [x] 💚 99% simillar to WeChat style.
 - [x] 📷 Image asset support
   - [x] 🔬HEIC/HEIF Image type support
@@ -214,13 +216,21 @@ Image(image: AssetEntityImageProvider(asset, isOriginal: false))
 Check the example for how it displays.
 
 ### Register assets change observe callback
+
 ```dart
 AssetPicker.registerObserve(); // Register callback.
 ```
 ```dart
 AssetPicker.unregisterObserve(); // Unregister callback.
 ```
 
+### Customize with your own type or UI
+
+`AssetPickerBuilderDelegate`, `AssetPickerViewerBuilderDelegate`, `AssetPickerProvider` and
+`AssetPickerViewerProvider` are all exposed and overridable. You can extends them and use your own
+type with generic type <A: Asset, P: Path>, then implement abstract methods. See the `Custom` page
+in the example which implements a picker with <File, Directory>.
+
 ## Classes Introduction 💭
 
 ### `AssetEntity`

pubspec.yaml

@@ -1,5 +1,5 @@
 name: wechat_assets_picker
-description: An assets' picker written in pure Dart which looks like the one in WeChat, support multi asset pick from the device.
+description: An audio/video/image picker in pure Dart which is the same with WeChat, support multi picking.
 version: 5.0.0-nullsafety.5
 homepage: https://github.com/fluttercandies/flutter_wechat_assets_picker