Update appextension_getpublicfolderasync_353057648.md

Author: ChrisGuzak

windows.applicationmodel.appextensions/appextension_getpublicfolderasync_353057648.md

@@ -11,15 +11,16 @@ public Windows.Foundation.IAsyncOperation<Windows.Storage.StorageFolder> GetPubl
 
 ## -description
 
-Gets the readable subfolder in the extension's isolated storage.
+Gets the subfolder provided by the `PublicFolder` attribute in the app extension for sharing files between the extension and the host.
 
 ## -returns
 
 The public sub-folder.
 
 ## -remarks
 
-An extension can provide a subfolder containing files that hosting apps can read from. Hosts cannot write to the folder.
+Extensions must create this folder by populating it with files as part of their package defintion. It is read-only to both the
+extension and its host.
 
 ## -examples