docs: update backup-restore.md DOC-937 (#1858) (#1860)

* Update backup-restore.md

notify end users this is not supported currently for self-hosted installations using helm chart.

* docs: added warning DOC-937

---------

Co-authored-by: Karl Cardenas <karl@spectrocloud.com>
(cherry picked from commit d105dfb)

Co-authored-by: hausmckinney <87979608+hausmckinney@users.noreply.github.com>

docs/docs-content/enterprise-version/system-management/backup-restore.md

@@ -15,6 +15,11 @@ You can enable backup and restore for your self-hosted Palette cluster to ensure
 
 * Amazon Simple Storage Service (S3) - Send the backup data of your enterprise cluster to object storage using AWS S3. Refer to the [S3](#s3) section for more information.
 
+:::caution
+
+Backup and Restore is not supported for self-hosted installations using the Helm Chart. 
+
+:::
 
 ## FTP
 
@@ -144,4 +149,4 @@ Use the following instructions to configure S3 backup for your enterprise cluste
 
 ### Validate
 
-Validation is part of the backup configuration wizard. You can validate a backup initiates at the scheduled time and successfully uploads to the S3 bucket. 
+Validation is part of the backup configuration wizard. You can validate a backup initiates at the scheduled time and successfully uploads to the S3 bucket.