Add release note for etcd backup default change

docs/cluster_spec.md

@@ -244,7 +244,20 @@ etcdClusters:
 ### etcd backups retention
 {{ kops_feature_table(kops_added_default='1.18') }}
 
-You can set the retention duration for the hourly and daily backups by defining env vars:
+As of kOps 1.27, the default etcd backup retention duration is 90 days.  
+You can adjust the retention duration using the `backupRetentionDays` parameter:
+
+```yaml
+etcdClusters:
+- etcdMembers:
+  - instanceGroup: master-us-east-1a
+    name: a
+  name: main
+  manager:
+    backupRetentionDays: 30
+```
+
+For older kOps versions, you set the retention duration for the hourly and daily backups by defining env vars:
 
 ```yaml
 etcdClusters:

docs/operations/etcd_backup_restore_encryption.md

@@ -22,8 +22,8 @@ Backups are done periodically and before cluster modifications using [etcd-manag
 are stored in object storage (like S3) together with the cluster configuration.
 
 By default, backups are taken every 15 min. Hourly backups are kept for 1 week and
-daily backups are kept for 1 year, before being automatically removed. The retention
+daily backups are kept for 90 days (or 2 years before kOps 1.27), before being automatically removed.
-duration for backups [can be adjusted](../cluster_spec.md#etcd-backups-retention)
+The retention duration for backups [can be adjusted](../cluster_spec.md#etcd-backups-retention)
 to suit other needs.
 
 ## Restore backups

docs/releases/1.27-NOTES.md

@@ -6,6 +6,9 @@ This is a document to gather the release notes prior to the release.
 
 # Significant changes
 
+* The default retention duration for the etcd backups is now set to 90 days.
+This behaviour can be overridden by setting `spec.etcdClusters[*].manager.backupRetentionDays` in the cluster spec.
+
 ## AWS
 
 * As of Kubernetes version 1.27, all nodes will default to running with instance-metadata-service tokens required, with a max hop limit of 1.