Update network-security-perimeter-concepts.md

Author: ChaithanyaRai

articles/private-link/network-security-perimeter-concepts.md

@@ -101,6 +101,14 @@ A network security perimeter-aware private link resource is a PaaS resource that
 > [!NOTE]
 > Refer to the respective private link resource documentation for information on currently unsupported scenarios.
 
+## Supported access rules' types
+
+Direction | Access rule type | 
+|---------------------------|---------------|
+Inbound | Subscription based rules |
+Inbound | IP based rules (check respective onboarded private link resources for v6 support)| 
+Outbound | FQDN based rules |
+
 ## Limitations of a network security perimeter
 
 ### Regional limitations