Fix issue #157

Add the usage of the file and that it is empty initially and meant
for the user to add the client documents and close after that.

docs/UserGuide.md

@@ -294,7 +294,7 @@ Examples:
 
 ### Storing documents of a client: `file`
 
-Creates/opens up a folder specific to a client for storing of their documents
+Creates/opens up a folder specific to a client for storing of their documents. When it is first created, it will be empty. We can add client's documents into the file and it will be saved in the file after closing the window.
 
 Format 1: `file <INDEX>`