Add descriptions for some VTK modules.

Filters/Hybrid/vtk.module

Filters/Modeling/vtk.module

Filters/OpenTURNS/vtk.module

Filters/Parallel/vtk.module

Filters/ParallelDIY2/vtk.module

Filters/ParallelFlowPaths/vtk.module

Filters/ParallelGeometry/vtk.module

Filters/ParallelImaging/vtk.module

Filters/ParallelMPI/vtk.module

Filters/ParallelStatistics/vtk.module

Filters/ParallelVerdict/vtk.module

Filters/Points/vtk.module

Filters/Programmable/vtk.module

Filters/Python/vtk.module

Filters/Reduction/vtk.module

Filters/ReebGraph/vtk.module

Filters/SMP/vtk.module

Filters/Selection/vtk.module

Filters/Sources/vtk.module

Filters/Statistics/vtk.module