message: update changelog, and minor section about the MPI module
diff: @@ -2398,3 +2398,10 @@ This version is the equivalent of:
  - return `ospGetVariance(fb)`
  This version is closest to `ospRenderFrame` from OSPRay v1.x.
  +
  +Distributed rendering with MPI
  +------------------------------
  +
  +The OSPRay MPI module is now a stand alone repository. It can be found on
  +GitHub [here](https://github.com/ospray/module_mpi), where all code and
  +documentation can be found.
  