Doc update

Author: Cerlin

README.md

@@ -51,7 +51,7 @@ $app_auth_instance = $box_sdk->getAppAuthClient($app_auth_info);
 
     ```
     1. getFolderInfo($folder_id); // Defaults to root folder (id = 0)
-    2. getFolderItems($folder_id); // Defaults to root folder (id = 0)
+    2. getFolderItems($folder_id = 0, $fields = [], $limit = 100, $offset = 0); // Defaults to root folder (id = 0)
     3. create($folder_name, $parent_folder_id = 0)
     4. delete($folder_id, $recursive = false, $e_tag = null)
     5. getTrashedItems()
@@ -81,4 +81,4 @@ $app_auth_instance = $box_sdk->getAppAuthClient($app_auth_info);
 ##### NOTE:
 
 1. All APIs return `\GuzzleHttp\Psr7\Response` (to get the body use `$response->getBody()->getContents()`. Refer [Guzzle HTTP Messages](http://docs.guzzlephp.org/en/latest/psr7.html#responses)) except `getEmbedUrl($file_id)` which returns string. 
-2. Guzzle related exceptions and its documentation can be found in [Guzzle Docs](http://docs.guzzlephp.org/en/latest/quickstart.html#exceptions)
+2. Guzzle related exceptions and its documentation can be found in [Guzzle Docs](http://docs.guzzlephp.org/en/latest/quickstart.html#exceptions)