update toc

Author: vhorne

articles/firewall/toc.yml

@@ -48,7 +48,7 @@ items:
     href: ../virtual-network/nat-gateway/tutorial-hub-spoke-nat-firewall.md?toc=%2fazure%2ffirewall%2ftoc.json
 - name: Concepts
   items:
-    - name: SKU
+    - name: Versions
       items:
       - name: Basic
         items:
@@ -69,7 +69,7 @@ items:
         - name: IDPS signature rule categories
           href: idps-signature-categories.md
 
-      - name: Choose an Azure Firewall SKU
+      - name: Choose an Azure Firewall version
         href: choose-firewall-sku.md
     - name: Preview
       items: