Slightly improve changelog for CW agent version change

Author: lukeseawalker

CHANGELOG.md

@@ -5,7 +5,7 @@ CHANGELOG
 -----
 
 **BUG FIXES**
-- Pin to version 1.247347.6b250880 of the CloudWatch agent due to performance impact of current latest version.
+- Pin to version 1.247347 of the CloudWatch agent due to performance impact of latest CW agent version 1.247348.
 
 2.11.0
 ------