add doc

Signed-off-by: Nesterzhou <ester.zhou@huawei.com>

en/application-dev/reference/arkui-ts/ts-basic-components-radio.md

+# Radio
+
+> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
+> This component is supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.
+
+
+The **\<Radio>** component allows users to select from a set of mutually exclusive options.
+
+
+## Required Permissions
+
+None
+
+
+## Child Components
+
+None
+
+
+## APIs
+
+Radio(options: {value: string, group: string})
+
+- Parameters
+  | Name| Type| Mandatory| Default Value| Description| 
+  | -------- | -------- | -------- | -------- | -------- |
+  | value | string | Yes| - | Value of the current radio button.|
+  | group | string | Yes| - | Name of the group to which the radio button belongs. Only one radio button in a given group can be selected at a time.|
+
+
+## Attributes
+
+| Name| Type| Default Value| Description| 
+| -------- | -------- | -------- | -------- |
+| checked | boolean | false | Whether the radio button is selected.| 
+
+
+## Events
+
+| Name| Description| 
+| -------- | -------- |
+| onChange(callback: (value: boolean) => void) | Triggered when the selected state of the radio button changes.<br> -The value **true** means that the radio button is selected.<br> -The value **false** means that the radio button is not selected.| 
+
+
+## Example
+
+```
+@Entry
+@Component
+struct RadioExample {
+  build() {
+    Flex({ direction: FlexDirection.Row, justifyContent: FlexAlign.Center, alignItems: ItemAlign.Center }) {
+      Column() {
+        Text('Radio1')
+        Radio({ value: 'Radio1', group: 'radioGroup' }).checked(true)
+          .height(50)
+          .width(50)
+          .onChange((value: boolean) => {
+            console.log('Radio1 status is ' + value)
+          })
+      }
+      Column() {
+        Text('Radio2')
+        Radio({ value: 'Radio2', group: 'radioGroup' }).checked(false)
+          .height(50)
+          .width(50)
+          .onChange((value: boolean) => {
+            console.log('Radio2 status is ' + value)
+          })
+      }
+      Column() {
+        Text('Radio3')
+        Radio({ value: 'Radio3', group: 'radioGroup' }).checked(false)
+          .height(50)
+          .width(50)
+          .onChange((value: boolean) => {
+            console.log('Radio3 status is ' + value)
+          })
+      }
+    }.padding({ top: 30 })
+  }
+}
+```
+![](figures/radio.gif)