fix TOC

Author: markingmyname

articles/postgresql/TOC.yml

@@ -458,17 +458,16 @@
     items:
     - name: Network setup
       href: migrate/migration-service/how-to-network-setup-migration-service.md
+  - name: Troubleshoot
+    items:
+    - name: Error codes
+      href: migrate/migration-service/troubleshoot-error-codes-migration-service.md
 - name: Migrate data with pg_dump
   href: migrate/how-to-migrate-using-dump-and-restore.md
 - name: Minimal-downtime migration with DMS
   href: single-server/how-to-migrate-online.md
 - name: Migrate from Oracle
   href: single-server/how-to-migrate-from-oracle.md
-  - name: Troubleshoot
-    items:
-    - name: Error codes
-      href: migrate/migration-service/troubleshoot-error-codes-migration-service.md
-
 - name: Azure Database for PostgreSQL - Single Server
   expanded: false
   items: