add clarification to impact of special bonds to manybody potentials

potentials, though such bonds may exist elsewhere in your system,

e.g. when using the "pair_style hybrid"_pair_hybrid.html command.

Thus LAMMPS ignores special_bonds settings when manybody potentials

are calculated.

are calculated.  Please note, that the existence of explicit bonds

for atoms that are described by a manybody potential will alter the

neigborlist and thus can render the computation of those interactions

invalid, since those pairs are not only used to determine direct

pairwise interactions but also neighbors of neighbors and more.

The recommended course of action is to remove such bonds, or - if

that is not possible - use a special bonds setting of 1.0 1.0 1.0.

NOTE: Unlike some commands in LAMMPS, you cannot use this command

multiple times in an incremental fashion: e.g. to first set the LJ