Add attribution control to typescript index exports (#1314)

src/index.d.ts

@@ -29,6 +29,7 @@ export {default as Layer} from './components/layer';
 export {default as BaseControl} from './components/base-control';
 export {default as Marker} from './components/marker';
 export {default as Popup} from './components/popup';
+export {default as AttributionControl} from './components/attribution-control';
 export {default as FullscreenControl} from './components/fullscreen-control';
 export {default as GeolocateControl} from './components/geolocate-control';
 export {default as NavigationControl} from './components/navigation-control';