Note removal of native-image-agent build-option in CHANGELOG

Author: olpaw

substratevm/CHANGELOG.md

@@ -6,6 +6,7 @@ This changelog summarizes major changes to GraalVM Native Image.
 * (GR-48304) Red Hat added support for the JFR event ThreadAllocationStatistics.
 * (GR-48343) Red Hat added support for the JFR events AllocationRequiringGC and SystemGC.
 * (GR-48612) Enable `--strict-image-heap` by default. The option is now deprecated and can be removed from your argument list. A blog post with more information will follow shortly.
+* (GR-48354) Remove native-image-agent legacy `build`-option
 
 ## GraalVM for JDK 21 (Internal Version 23.1.0)
 * (GR-35746) Lower the default aligned chunk size from 1 MB to 512 KB for the serial and epsilon GCs, reducing memory usage and image size in many cases.