Fix changelog pending format (#5065)

Author: isaiahvita

CHANGELOG_PENDING.md

@@ -1,6 +1,7 @@
 ### SDK Features
 
 ### SDK Enhancements
-"x-amz-expected-bucket-owner" header was added to the list of headers that need to be presigned
+* `aws/signer/v4`: Add bucket owner header to presigned list.
+  * Add x-amz-expected-bucket-owner header to the list of headers that need to be presigned.
 
 ### SDK Bugs