message: DOC: document openmp detection changes
diff: @@ -16,6 +16,10 @@ The Axom project release numbers follow [Semantic Versioning](http://semver.org/
  ### Deprecated
  ### Changed
  +- AXOM_USE_OPENMP is now being set at configure time accordingly instead of
  + auto-detected based on whether "_OPENMP" is passed by the compiler. This
  + fixes issues where a host code would compile Axom w/out OpenMP, but, use
  + Axom in parts of the code where OpenMP is enabled.
  ### Fixed
  