update Fedora rpm docu

lammps-openmpi-devel), the header for compiling programs using

the C library interface (lammps-headers), and the LAMMPS python

module for Python 3. All packages can be installed at the same

time and the name of the LAMMPS executable is {lmp} in all 3 cases.

By default, {lmp} will refer to the serial executable, unless

one of the MPI environment modules is loaded

time and the name of the LAMMPS executable is {lmp} and {lmp_openmpi}

or {lmp_mpich} respectively.  By default, {lmp} will refer to the

serial executable, unless one of the MPI environment modules is loaded

("module load mpi/mpich-x86_64" or "module load mpi/openmpi-x86_64").

Then the corresponding parallel LAMMPS executable is used.

Then the corresponding parallel LAMMPS executable can be used.

The same mechanism applies when loading the LAMMPS python module.

To install LAMMPS with OpenMPI and run an input in.lj with 2 CPUs do: