Added documentation for File Explorer shortcuts

docs/lang/dev-en-HK/5.md

@@ -10,6 +10,7 @@ In simple words, the file system of ArOZ Online System consists of the following
 - File Selector
 - File Explorer Shortcuts
 - File Extension Default Opener
+- New Item Menu
 
 In this page, the functions and the API of the elements above will be introduced.
 
@@ -292,5 +293,50 @@ function addFileFromSelector(fileData){
 ```
 
 ## File Explorer Shortcuts
+The file explorer shortcuts is a set of ```.shortcut``` files located under user profile directory. The .shortcut files contains the following information, each data is seperated by a newline. (\n or \r\n depends on your host device operating system).
+
+```
+foldershrct
+{Name of the shortcut}
+{Path of the shortcut relative to /AOR}
+{icon of the shortcut, reference from system default css}
+```
+
+For example, here is a shortcut for the Audio module's uploads directory which points to ```Audio/uploads``` and with a music icon.
+
+```
+foldershrct
+Musics
+Audio/uploads
+music icon
+```
+
+
+To modify the default shortcuts, your WebApp can add files into the ```file_system/fshortcut``` directory. If your WebApp needs to add shortcuts to the file explorer for a particular user, you might need to access the local user configuration folder which is usually under ```/etc/AOB/users/{username}/SystemAOB/functions/file_system/fshortcut/*.shorcut```. 
+
+To get the full path of the user configuration directory, we recommend using the functions inside ```functions/users/userIsolation.php``` instead.
+
+```
+<?php
+//Assume your username is "alan"
+include_once("../SystemAOB/functions/user/userIsolation.php");
+$configs = glob(getUserDirectory() . "SystemAOB/functions/file_system/fshortcut/*.shortcut");
+var_dump($configs);
+?>
+
+Returned value
+
+C:\wamp\www\private\AOB\YourWebApp\index.php:5:
+array (size=4)
+  0 => string '/etc/AOB/users/alan/SystemAOB/functions/file_system/fshortcut/1555308037.shortcut' (length=77)
+  1 => string '/etc/AOB/users/alan/SystemAOB/functions/file_system/fshortcut/1555308041.shortcut' (length=77)
+  2 => string '/etc/AOB/users/alan/SystemAOB/functions/file_system/fshortcut/1557888190.shortcut' (length=77)
+  3 => string '/etc/AOB/users/alan/SystemAOB/functions/file_system/fshortcut/1557888194.shortcut' (length=77)
+```
+
+
+## File Extension Default Opener
+
+## New Item Menu
+
 
-## File Extension Default Opener