Fixed typo in paper demos.

5 jobs for master in 16 minutes and 54 seconds
Status Name Job ID Coverage
  Test
passed test_min #239809

00:03:17

passed test_mpi #239810

00:05:34

passed test_mpi_fftw #239811

00:06:21

passed test_mpi_fftw_hdf5 #239812

00:10:34

64.0%
 
  Release
passed release_image_master #239813

00:06:19