Added BitLocker enabled as prerequisite

Feedback from customers - Steven/Manu/Madhuri

Author: alkohli

articles/databox/data-box-disk-deploy-set-up.md

@@ -13,7 +13,7 @@ ms.devlang: NA
 ms.topic: tutorial
 ms.tgt_pltfrm: NA
 ms.workload: NA
-ms.date: 07/10/2018
+ms.date: 08/28/2018
 ms.author: alkohli
 Customer intent: As an IT admin, I need to be able to order Data Box Disk to upload on-premises data from my server onto Azure.
 ---
@@ -36,7 +36,8 @@ Before you begin, make sure that:
 3. You have a host computer on which you can install the Data Box Disk unlock tool. Your host computer must
     - Run a [Supported operating system](data-box-disk-system-requirements.md).
     - Have [Windows PowerShell 4 installed](https://www.microsoft.com/download/details.aspx?id=40855).
-    - Have [.NET Framework 4.5 installed](https://www.microsoft.com/download/details.aspx?id=30653).
+    - Have [.NET Framework 4.5.1 installed](https://www.microsoft.com/download/details.aspx?id=30653).
+    - Have BitLocker enabled. For more information, see how to [Enable BitLocker on Windows 2012 R2 systems](http://thesolving.com/storage/how-to-enable-bitlocker-on-windows-server-2012-r2/).
 
 ## Unpack your disks