Add DNS article to TOC.

Author: wmgries

articles/storage/files/TOC.yml

@@ -98,6 +98,8 @@
     items:
     - name: Configure Azure Files network endpoints
       href: storage-files-networking-endpoints.md
+    - name: Configuring DNS forwarding for Azure Files
+      href: storage-files-networking-dns.md
     - name: Configure Site-to-Site VPN 
       href: storage-files-configure-s2s-vpn.md
     - name: Configure Point-to-Site VPN on Windows