fix: correct typo inject as service -> inject (rust-lang#409)

Author: jacobq

text/0398-RouteInfo-Metadata.md

@@ -11,7 +11,7 @@ The RFC introduces the ability to associate application specific metadata with i
 ```js
 // app/route/profile.js
 import Route from '@ember/routing/route';
-import { inject as service } from '@ember/service';
+import { inject } from '@ember/service';
 
 export default Route.extend({
   user: inject('user'),