add release notes

Author: white238

RELEASE-NOTES.md

@@ -23,6 +23,7 @@ The project release numbers follow [Semantic Versioning](http://semver.org/spec/
   not the C language.
 - Guard HIP C smoketest against projects that don't enable C as a language in their projects.
 - Changes benchmark custom target `run_benchmarks` to exclusively run benchmarks (not other general tests).
+- Fix HIP smoketests to fail on HIP errors.
 
 ## [Version 0.6.2] - Release date 2024-03-15