Fix include syntax for virtual machines isolation

Corrected the syntax for including the virtual machines common isolation content.

Author: rmca14

articles/security/fundamentals/isolation-choices.md

@@ -104,7 +104,7 @@ Microsoft Azure provides various cloud-based computing services that include a w
 
 ### Isolated Virtual Machine Sizes
 
-[!INCLUDE [virtual-machines-common-isolation](~/reusable-content/ce-skilling/azure/includes/virtual-machines-common-isolation.md)]
+<! [!INCLUDE [virtual-machines-common-isolation](~/reusable-content/ce-skilling/azure/includes/virtual-machines-common-isolation.md)] >
 
 ### Dedicated hosts