List transition example fix (#2611)

* reset id for new items

* more consistent syntax for composition api

Author: AloisSeckar

src/examples/src/list-transition/App/composition.js

@@ -14,6 +14,7 @@ export default {
 
     function reset() {
       items.value = getInitialItems()
+      id = items.value.length + 1
     }
 
     function shuffle() {

src/examples/src/list-transition/App/options.js

@@ -16,6 +16,7 @@ export default {
     },
     reset() {
       this.items = getInitialItems()
+      id = getInitialItems().length + 1
     },
     shuffle() {
       this.items = shuffle(this.items)