UF3 Lammps code update, script fix and documentation update

• [x] lammps_plugin/scripts/generate_uf3_lammps_pots.py has been updated to add UNITS, AUTHOR, DATE and CITATION metadata
• [x] The documentation regarding pair_style line for setting uf3 as the pair style in LAMMPS has been updated.
• [ ] Updates to the UF3 LAMMPS code to match the code in https://github.com/uf3/lammps/tree/ml-uf3