Added create index documentation

README.md

@@ -254,7 +254,18 @@ Schema::create('users', function($collection)
     $collection->unique('email');
 });
 ```
+You can also pass all the parameter specified in the MongoDB docs [here](https://docs.mongodb.com/manual/reference/method/db.collection.createIndex/#options-for-all-index-types) in the `$options` parameter. For example:
 
+```
+Schema::create('users', function($collection)
+{
+    $collection->index('username',null,null,[
+                    'sparse' => true,
+                    'unique' => true,
+                    'background' => true
+    ]);
+});
+```
 Supported operations are:
 
  - create and drop