fix syntax errors in code examples for ember-data

Author: eflanagan0

guides/release/models/handling-metadata.md

@@ -66,7 +66,7 @@ After reading it, `meta.total` can be used to calculate how many pages of posts
 To use the `meta` data outside of the `model` hook, you need to return it:
 
 ```javascript {data-filename=app/routes/users.js}
-import Router from '@ember/routing/route';
+import Route from '@ember/routing/route';
 
 export default Route.extend({
   model() {

guides/release/models/pushing-records-into-the-store.md

@@ -83,7 +83,7 @@ serializer before pushing it into the store, you can use the
 ```javascript {data-filename=app/serializers/album.js}
 import DS from 'ember-data';
 
-export default DS.RestSerializer.extend({
+export default DS.RESTSerializer.extend({
   normalize(typeHash, hash) {
     hash['songCount'] = hash['song_count']
     delete hash['song_count']