added description of the LAMMPS configurations and build page

added missing subsection title

added PLUMED installation instructions and compiling of LAMMPS with the PLUMED PKG

changed cmake options in READNE

fixed hyperlink address

renamed main.md and updated README about it

updated description to reflect renaming of build dir

renamed directory

added tree structure

added subsection titles

added KOKKOS-CUDA-OMP and KOKKOS-OMP sections

added check system resources and updated description

added and tested test/

finished KOKKOS-CUDA install config and test

started writing up MPI, KOKKOS-CUDA installations