Fixing documentation for Sparse grid

example/SparseGrid/1_gray_scott_3d_sparse/main.cpp

example/SparseGrid/1_gray_scott_3d_sparse_gpu/main.cu

example/SparseGrid/2_gray_scott_3d_sparse_gpu_opt/Makefile

example/SparseGrid/2_gray_scott_3d_sparse_gpu_opt/config.cfg

example/SparseGrid/2_gray_scott_3d_sparse_gpu_opt/main.cu

example/SparseGrid/2_gray_scott_3d_sparse_opt/Makefile

example/SparseGrid/2_gray_scott_3d_sparse_opt/config.cfg

example/SparseGrid/2_gray_scott_3d_sparse_opt/main.cpp

example/SparseGrid/3_gray_scott_3d_sparse_cs/Makefile

example/SparseGrid/3_gray_scott_3d_sparse_cs/config.cfg

example/SparseGrid/3_gray_scott_3d_sparse_cs/main.cpp

example/SparseGrid/3_gray_scott_3d_sparse_gpu_cs/Makefile

example/SparseGrid/3_gray_scott_3d_sparse_gpu_cs/config.cfg

example/SparseGrid/3_gray_scott_3d_sparse_gpu_cs/main.cu

...ple/SparseGrid/3_gray_scott_3d_sparse_gpu_cs_opt/Makefile

...e/SparseGrid/3_gray_scott_3d_sparse_gpu_cs_opt/config.cfg

example/SparseGrid/3_gray_scott_3d_sparse_gpu_cs_opt/main.cu

...ple/SparseGrid/4_gray_scott_3d_sparse_surface_cs/Makefile

...e/SparseGrid/4_gray_scott_3d_sparse_surface_cs/config.cfg

...ple/SparseGrid/4_gray_scott_3d_sparse_surface_cs/main.cpp