fix route transitions example

examples/routes-transitions/pages/users.vue

@@ -19,6 +19,11 @@
 import axios from 'axios'
 
 export default {
+  // Watch for $route.query.page to call Component methods (asyncData, fetch, validate, layout, etc.)
+  watchQuery: ['page'],
+  // Key for <nuxt-child> (transitions)
+  key: (to) => to.fullPath,
+  // Called to know which transition to apply
   transition(to, from) {
     if (!from) return 'slide-left'
     return +to.query.page < +from.query.page ? 'slide-right' : 'slide-left'