Add changelog entry.

Author: fniephaus

substratevm/CHANGELOG.md

@@ -15,6 +15,7 @@ This changelog summarizes major changes to GraalVM Native Image.
 * (GR-46064) Add option `-H:±IndirectBranchTargetMarker` to mark indirect branch targets on AMD64 with an endbranch instruction. This is a prerequisite for future Intel CET support.
 * (GR-46740) Add support for foreign downcalls (part of "Project Panama") on the AMD64 platform.
 * (GR-27034) Add `-H:ImageBuildID` option to generate Image Build ID, which is a 128-bit UUID string generated randomly, once per bundle or digest of input args when bundles are not used.
+* (GR-47647) Add `-H:±UnlockExperimentalVMOptions` for unlocking access to experimental options similar to HotSpot's `-XX:UnlockExperimentalVMOptions`. Explicit unlocking will be required in a future release, which can be tested with the env setting `NATIVE_IMAGE_EXPERIMENTAL_OPTIONS_ARE_FATAL=true`. For more details, see [issue #7105](https://github.com/oracle/graal/issues/7105).
 
 ## GraalVM for JDK 17 and GraalVM for JDK 20 (Internal Version 23.0.0)
 * (GR-40187) Report invalid use of SVM specific classes on image class- or module-path as error. As a temporary workaround, `-H:+AllowDeprecatedBuilderClassesOnImageClasspath` allows turning the error into a warning.