Update changelog entry

Author: jterapin

gems/aws-sdk-core/CHANGELOG.md

@@ -1,7 +1,7 @@
 Unreleased Changes
 ------------------
 
-* Issue - Document retry behaviors in `InstanceProfileCredentials`.
+* Issue - Refactor `InstanceProfileCredentials` to improve code clarity and documentation. 
 
 3.226.2 (2025-07-01)
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