📖 update README.md and remove data object, fixes #22

Author: gabrielstuff

README.md

@@ -55,8 +55,10 @@ Vue.use(IdleVue, {
 
 const vm = new Vue({
  el: '#app',
- data: {
- messageStr: "Hello"
+ data () {
+ return {
+ messageStr: 'Hello'
+ }
  },
  onIdle() {
  this.messageStr = "ZZZ"