Update CHANGELOG.md

Author: loicottet

substratevm/CHANGELOG.md

@@ -13,6 +13,7 @@ This changelog summarizes major changes to GraalVM Native Image.
 * (GR-68984) Ship the `reachability-metadata-schema.json` together with GraalVM at `<graalvm-home>/lib/svm/schemas/reachability-metadata-schema.json`.
 * (GR-68984) Improve the schema to capture detailed constraints about each element in the `reachability-metadata-schema.json`.
 * (GR-70046) Remove all support for running image builder on classpath.
+* (GR-69577) Retire `--future-defaults=complete-reflection-types`. All reflective operations on types registered for reflection will now return complete results.
 
 ## GraalVM 25
 * (GR-52276) (GR-61959) Add support for Arena.ofShared().