feat(components): [config-provider] add message plain config (#20723)

* feat(components): [config-provider] add message plain config

* feat: update

docs/en-US/component/config-provider.md

@@ -95,6 +95,7 @@ In this section, you can learn how to use Config Provider to provide experimenta
 | duration ^(2.8.2)  | display duration, millisecond. If set to 0, it will not turn off automatically | ^[number]  | —       |
 | showClose ^(2.8.2) | whether to show a close button                                                 | ^[boolean] | —       |
 | offset ^(2.8.2)    | set the distance to the top of viewport                                        | ^[number]  | —       |
+| plain ^(2.9.11)    | whether message is plain                                                       | ^[boolean] | —       |
 
 ### Config Provider Slots
 

docs/examples/config-provider/message.vue

@@ -11,6 +11,7 @@ import { reactive } from 'vue'
 import { ElMessage } from 'element-plus'
 const config = reactive({
   max: 3,
+  plain: true,
 })
 const open = () => {
   ElMessage('This is a message.')