update README.md

Author: wenlng

README.md

@@ -197,14 +197,17 @@ interface RotateEvents {
 
 ### params
 ```ts
-interface _ {
-  config?: ButtonConfig;
-  clickEvent?: () => void;   // event -> @clickEvent=""
+interface $Attr {
+  config?: CaptchaConfig;
   disabled?: boolean;
   type?: "default" | "warn" | "error" | "success";
   title?: string;
 }
 
+interface $Event {
+  clickEvent?: Event;     // event -> @clickEvent=""
+}
+
 export interface ButtonConfig {
   width?: number;
   height?: number;