Added details of Windows OS Patches included

Added details of KB4132216 and KB4338822

Author: apwestgarth

articles/azure-stack/azure-stack-app-service-release-notes-update-three.md

@@ -66,6 +66,10 @@ Azure App Service on Azure Stack Update 3 includes the following improvements an
   - Added Wincache 2.0.0.8
   - Updated Git for Windows to v 2.17.1.2
   - Updated Kudu to 74.10611.3437
+  
+ - **Updates to underlying operating system of all roles**:
+  - [Servicing stack update for Windows Server 2016 for x64-based Systems (KB4132216)](https://support.microsoft.com/help/4132216/servicing-stack-update-for-windows-10-1607-may-17-2018)
+  - [2018-07 Cumulative Update for Windows Server 2016 for x64-based Systems (KB4338822)](https://support.microsoft.com/help/4338822/windows-10-update-kb4338822)
 
 ### Post Update Steps (optional)