Update trusted-launch-portal.md

To inform customer some Linux distribution might have unsigned drivers which makes SB difficult to use since the system will not boot, since it is looking for signed drivers to start up.

Author: Howie425

articles/virtual-machines/trusted-launch-portal.md

@@ -26,8 +26,10 @@ ms.custom: template-how-to, devx-track-azurecli, devx-track-azurepowershell
 
     - Configure machines to automatically install the Azure Monitor and Azure Security agents on virtual machines 
 - Make sure that the firewall policies are allowing access to *.attest.azure.net
+-  > [!NOTE]
+    >  If you are using a Linux image and anticipate the VM may have kernel drivers either unsigned or not signed by the Linux distro vendor, then you may want to consider turning off secure boot. In Portal, in the ‘Create a virtual machine’ page for ‘Security type’ parameter with ‘Trusted Launch Virtual Machines’ selected, click on ‘Configure security features’ and uncheck the ‘Enable secure boot’ checkbox. In CLI, PowerShell, or SDK, set secure boot parameter to false.
+
 
- 
 ## Deploy a trusted launch VM
 Create a virtual machine with trusted launch enabled. Choose an option below: