Merge pull request #62 from ClickHouse/aashishkohli-patch-8

Update upgrades.md

Author: gingerwizard

docs/en/cloud/manage/upgrades.md

@@ -10,6 +10,12 @@ import ScalePlanFeatureBadge from '@theme/badges/ScalePlanFeatureBadge'
 
 With ClickHouse Cloud you never have to worry about patching and upgrades. We roll out upgrades that include fixes, new features and performance improvements on a periodic basis. For the full list of what is new with ClickHouse refer to our [Cloud changelog](/docs/en/cloud/reference/changelog.md).
 
+:::note	
+We are introducing a new upgrade mechanism, a concept we call "make before break" (or MBB). With this new approach, we add updated replica(s) before removing the old one(s) during the upgrade operation. This results in more seamless upgrades that are less disruptive to running workloads.	
+
+**As part of this change, historical system table data will be retained for up to a maximum of 30 days as part of upgrade events. In addition, any system table data older than December 19, 2024, for services on AWS or GCP and older than January 14, 2025, for services on Azure will not be retained as part of the migration to the new organization tiers.**
+:::	
+
 ## Version compatibility
 
 When you create a service, the [`compatibility` setting](/docs/en/operations/settings/settings#compatibility) is set to the most up-to-date ClickHouse version offered on ClickHouse Cloud at the time your service is initially provisioned.