message: DOC: update Release notes for v0.3.1 release
diff: @@ -9,6 +9,20 @@ The Axom project release numbers follow [Semantic Versioning](http://semver.org/
  ## [Unreleased] - Release date yyyy-mm-dd
  +### Added
  +
  +### Removed
  +
  +### Deprecated
  +
  +### Changed
  +
  +### Fixed
  +
  +### Known Bugs
  +
  +## [Version 0.3.1] - Release date 2019-07-22
  +
  ### Added
  - Added a new implementation of the Bounding Volume Hierarchy(BVH) spatial
  acceleration data-structure to spin. The new BVH implementation relies on RAJA
  