Declare config type for Group node

src/Group.ts

@@ -1,9 +1,11 @@
 import { Util } from './Util';
-import { Container } from './Container';
+import { Container, ContainerConfig } from './Container';
 import { _registerNode } from './Global';
 import { Node } from './Node';
 import { Shape } from './Shape';
 
+export interface GroupConfig extends ContainerConfig {}
+
 /**
  * Group constructor.  Groups are used to contain shapes or other groups.
  * @constructor

src/index-types.d.ts

@@ -83,6 +83,7 @@ declare namespace Konva {
 
   export const Group: typeof import('./Group').Group;
   export type Group = import('./Group').Group;
+  export type GroupConfig = import('./Group').GroupConfig;
 
   export const DD: typeof import('./DragAndDrop').DD;