Update NAT Gateway TOC troubleshoot entries to point to SupportArticles

Author: asudbring

articles/nat-gateway/toc.yml

@@ -63,12 +63,10 @@ items:
         href: monitor-nat-gateway-flow-logs.md
   - name: Troubleshoot
     items:
-      - name: Troubleshoot NAT gateway
-        href: troubleshoot-nat.md
-      - name: Troubleshoot NAT gateway connectivity
-        href: troubleshoot-nat-connectivity.md
-      - name: Troubleshoot NAT gateway and Azure services
-        href: troubleshoot-nat-and-azure-services.md
+      - name: Troubleshoot Azure NAT Gateway
+        href: https://learn.microsoft.com/troubleshoot/azure/nat-gateway/welcome-azure-nat-gateway?toc=/azure/nat-gateway/TOC.json
+  - name: Support and troubleshooting
+    href: nat-gateway-support-help.md
   - name: Reference
     items:
       - name: Azure CLI