fix path

Author: vhorne

articles/web-application-firewall/toc.yml

@@ -164,7 +164,7 @@
   - name: Azure CLI
     items:
     - name: Front Door
-      href: /cli/azure/front-door/waf-policy
+      href: /cli/azure/network/front-door/waf-policy
     - name: Application Gateway
       href: /cli/azure/network/application-gateway
     - name: CDN