Updating CHANGELOG for ec2_key wait addition

CHANGELOG.md

@@ -62,6 +62,7 @@ Other notable changes:
 * setup module code moved into module_utils/, facts now accessible by other modules  
 * synchronize module sets relative dirs based on inventory or role path
 * misc bugfixes and other parameters
+* the ec2_key module now has wait/wait_timeout parameters
 
 ## 1.5.3 "Love Walks In" - March 13, 2014