add copyright header

tools/tabulate/dihedral_harmonic_tabulate.py

@@ -1,4 +1,16 @@
 #!/usr/bin/env python
+# ----------------------------------------------------------------------
+#   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+#   https://www.lammps.org/ Sandia National Laboratories
+#   LAMMPS Development team: developers@lammps.org
+#
+#   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+#   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+#   certain rights in this software.  This software is distributed under
+#   the GNU General Public License.
+#
+#   See the README file in the top-level LAMMPS directory.
+# -------------------------------------------------------------------------
 
 from tabulate import DihedralTabulate