add agc rest api link

Author: halkazwini

articles/web-application-firewall/toc.yml

@@ -238,6 +238,8 @@ items:
       href: /rest/api/frontdoorservice/webapplicationfirewall/policies
     - name: Application Gateway
       href: /rest/api/application-gateway
+    - name: Application Gateway for Containers
+      href: /rest/api/applicationgatewaycontainers/security-policies-interface
   - name: .NET
     href: /dotnet/api
   - name: Java