[new feature] Toast: support multiple instance (#586)

docs/markdown/en-US/toast.md

@@ -62,6 +62,19 @@ export default {
 }
 ```
 
+#### Singleton
+Toast use singleton mode by default, if you need to pop multiple Toast at the same time, you can refer to the following example
+
+```js
+Toast.allowMultiple();
+
+const toast1 = Toast('First Toast');
+const toast2 = Toast.success('Second Toast');
+
+toast1.clear();
+toast2.clear();
+```
+
 ### Methods
 
 | Methods | Attribute | Return value | Description |
@@ -70,9 +83,10 @@ export default {
 | Toast.loading | `options | message` | toast instance | Show loading toast |
 | Toast.success | `options | message` | toast instance | Show success toast |
 | Toast.fail | `options | message` | toast instance | Show fail toast |
+| Toast.clear | `clearAll` | `void` | Close  |
+| Toast.allowMultiple | - | `void` | Allow multlple toast at the same time |
 | Toast.setDefaultOptions | `options` | `void` | Set default options of all toasts |
 | Toast.resetDefaultOptions | - | `void` | Reset default options of all toasts |
-| Toast.clear | - | `void` | Close  |
 
 ### Options
 

docs/markdown/zh-CN/toast.md

@@ -62,6 +62,18 @@ export default {
 }
 ```
 
+#### 单例模式
+Toast 默认采用单例模式，即同一时间只会存在一个 Toast，如果需要在同一时间弹出多个 Toast，可以参考下面的示例
+
+```js
+Toast.allowMultiple();
+
+const toast1 = Toast('第一个 Toast');
+const toast2 = Toast.success('第二个 Toast');
+
+toast1.clear();
+toast2.clear();
+```
 
 
 ### 方法
@@ -72,9 +84,10 @@ export default {
 | Toast.loading | `options | message` | toast 实例 | 展示加载提示 |
 | Toast.success | `options | message` | toast 实例 | 展示成功提示 |
 | Toast.fail | `options | message` | toast 实例 | 展示失败提示 |
+| Toast.clear | `clearAll` | `void` | 关闭提示 |
+| Toast.allowMultiple | - | `void` | 允许同时存在多个 Toast |
 | Toast.setDefaultOptions | `options` | `void` | 修改默认配置，对所有 Toast 生效 |
 | Toast.resetDefaultOptions | - | `void` | 重置默认配置，对所有 Toast 生效 |
-| Toast.clear | - | `void` | 关闭提示 |
 
 ### Options