Update note on Managed Identity for resource access

Clarified the importance of enabling Managed Identity for secure intra-perimeter communication and included a note on how MI might not be needed in some scenarios.

Author: shmallad

includes/network-security-perimeter-note-managed-id.md

@@ -11,4 +11,4 @@ ms.custom: include file, ignite-2024
 ---
 
 > [!NOTE]
-> If managed identity is not assigned to the resource which supports it, outbound access to other resources within the same perimeter will be denied. Subscription based inbound rules intended to allow access from this resource will not take effect.  
+> Enabling a Managed Identity (MI) is required to support intra-perimeter communication between resources. While some capabilities for certain resources (for example, Azure SQL's features that use platform‑managed, SQL‑to‑SQL backend communication) may continue to function without a MI, enabling one is strongly recommended to ensure secure access within the same perimeter or across linked perimeters.