toc update

Author: rajats22

articles/backup/toc.yml

@@ -801,6 +801,8 @@
       href: backup-azure-troubleshoot-slow-backup-performance-issue.md
     - name: Azure Backup Server
       href: backup-azure-mabs-troubleshoot.md
+    - name: Azure Backup Vault
+      href: backup-azure-backup-vault-troubleshoot.md
     - name: System Center DPM
       href: backup-azure-scdpm-troubleshooting.md
     - name: Azure File share