Update index.md

Fixed minor spelling issue i encountered while reading through the document.

index.md

@@ -1563,7 +1563,7 @@ Backbone.history.start();
 
 ### Backbone’s Sync API
 
-The Backbone.sync method is intended to be overridden to support other backends. The built-in method is tailed to a certain breed of RESTful JSON APIs – Backbone was originally extracted from a Ruby on Rails application, which uses HTTP methods like PUT the same way.
+The Backbone.sync method is intended to be overridden to support other backends. The built-in method is tailored to a certain breed of RESTful JSON APIs – Backbone was originally extracted from a Ruby on Rails application, which uses HTTP methods like PUT the same way.
 
 The way this works is the model and collection classes have a sync method that calls Backbone.sync. Both will call this.sync internally when fetching, saving, or deleting items.