Update index for kspace_style commands

.. index:: kspace_style

.. index:: kspace_style ewald

.. index:: kspace_style ewald/dipole

.. index:: kspace_style ewald/dipole/spin

.. index:: kspace_style ewald/disp

.. index:: kspace_style ewald/omp

.. index:: kspace_style pppm

.. index:: kspace_style pppm/kk

.. index:: kspace_style pppm/omp

.. index:: kspace_style pppm/gpu

.. index:: kspace_style pppm/intel

.. index:: kspace_style pppm/cg

.. index:: kspace_style pppm/dipole

.. index:: kspace_style pppm/dipole/spin

.. index:: kspace_style pppm/disp

.. index:: kspace_style pppm/disp/omp

.. index:: kspace_style pppm/disp/tip4p

.. index:: kspace_style pppm/disp/tip4p/omp

.. index:: kspace_style pppm/disp/intel

.. index:: kspace_style pppm/cg/omp

.. index:: kspace_style pppm/stagger

.. index:: kspace_style pppm/tip4p

.. index:: kspace_style pppm/tip4p/omp

.. index:: kspace_style msm

.. index:: kspace_style msm/omp

.. index:: kspace_style msm/cg

.. index:: kspace_style msm/cg/omp

.. index:: kspace_style scafacos

kspace_style command

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