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

also updates documentation surrounding the reorder & infinite scroll

fixes #16302

core/src/components/segment-button/usage/vue.md

@@ -141,7 +141,7 @@
   import { Component, Vue } from 'vue-property-decorator';
 
   @Component()
-  export default class MenuExample extends Vue {
+  export default class Example extends Vue {
     segmentButtonClicked(ev: any) {
       console.log('Segment button clicked', ev);
     }