addressed build warning

Author: AbhishekMallick01

articles/backup/index.yml

@@ -7,9 +7,6 @@ metadata:
   title: Azure Backup Documentation
   description: The Azure Backup service provides simple, secure, and cost-effective solutions to back up your data and recover it from the Microsoft Azure cloud.
   ms.service: azure-backup
-  ms.custom:
-    - ignite-2023
-    - ignite-2024
   ms.topic: landing-page
   author: jyothisuri
   ms.author: jsuri