rephrase note about kernel JIT recompilation and Kepler vs. the rest compatibility

.. note::

   NVIDIA GPUs with CC 5.0 (Maxwell) and newer are not compatible with

   CC 3.x (Kepler).  If you run Kokkos on a newer architecture than what

   LAMMPS was compiled with, there will be a significant delay during

   device initialization since the just-in-time compiler has to

   recompile the GPU kernel code for the new hardware.

   If you run Kokkos on a newer GPU architecture than what LAMMPS was

   compiled with, there will be a delay during device initialization

   since the just-in-time compiler has to recompile all GPU kernels

   for the new hardware.  This is, however, not possible when compiled

   for NVIDIA GPUs with CC 3.x (Kepler) for GPUs with CC 5.0 (Maxwell)

   and newer as they are not compatible.

The settings discussed below have been tested with LAMMPS and are

confirmed to work.  Kokkos is an active project with ongoing improvements