Update changelog

Summary: We want this changelog description to be more accurate

Reviewed By: ryantobinmeta

Differential Revision: D68037813

fbshipit-source-id: 3e490d6c28f561aa3905bdd51fc0e04b93a7f885

Author: maxalbrightmeta

CHANGELOG.md

@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [18.0.0]
 
 ### Added
-- Add support for in-app purchase auto-logging for Google Play Billing Libraries 5 through 7
+- Improved support for in-app purchase events for Google Play Billing Libraries 5 through 7
 
 ## [17.0.2]