add roles permissions entry

Author: raboilla

articles/firewall/toc.yml

@@ -91,6 +91,8 @@ items:
         href: policy-rule-sets.md
       - name: Policy Analytics
         href: policy-analytics.md
+    - name: Roles and permissions
+      href: roles-permissions.md  
     - name: Azure Firewall web categories
       href: web-categories.md
     - name: Infrastructure FQDNs