Add recent changes to changelog (#710)

Author: mirskifa

CHANGELOG.md

@@ -5,6 +5,8 @@
 * Updated to MQ version 9.4.1.0
 * Fix to diable FIPS mode for `runmqakm` key store generation, when FIPS is not enabled
 * Fix APAR IT46430
+* Changed build Dockerfile to reduce file duplication across image layers
+* Changed shutdown flow to continue reaping orphan processes during queue manager shutdown
 
 ## 9.4.0.0 (2024-06)