message: Add comment on default libCEED GPU backend.
diff: @@ -330,6 +330,8 @@ void Device::Setup(const int device)
  {
  if (!ceed_option)
  {
  + // NOTE: The current default libCEED GPU backend (ceed-cuda) uses
  + // atomics and therefore is non-deterministic!
  CeedDeviceSetup("/gpu/cuda/gen");
  }
  else
  