fix(reorder-group): remove required parameter for the complete method (#18084)

also updates documentation surrounding the reorder & infinite scroll

fixes #16302

core/src/components/loading/readme.md

@@ -138,7 +138,6 @@ export class LoadingExample extends Component<Props, State> {
     );
   }
 }
-
 ```
 
 

core/src/components/loading/usage/react.md

@@ -41,5 +41,4 @@ export class LoadingExample extends Component<Props, State> {
     );
   }
 }
-
 ```