Update CHANGELOG for #15725

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 3.13.0 (Unreleased)
 
+NOTES
+
+* data-source/aws_kms_secrets: The `id` attribute has changed to the name of the AWS Region. The first apply of this updated data source may show this difference. [GH-15725]
+
 FEATURES
 
 * **New Resource:** `aws_glue_resource_policy` [GH-10361]
@@ -15,6 +19,10 @@ ENHANCEMENTS
 * resource/aws_sagemaker_model: Add `container` configuration block `mode` argument [GH-15371]
 * resource/aws_sagemaker_notebook_instance: Add `url` and `network_interface_id` attributes [GH-15802]
 
+BUG FIXES
+
+* data-source/aws_kms_secrets: Prevent plan differences with the `id` attribute [GH-15725]
+
 ## 3.12.0 (October 22, 2020)
 
 FEATURES