fix typo

surrounding table values from which an energy or force is computed by

linear interpolation.

For the *spline* style, a cubic spline coefficients are computed and

For the *spline* style, cubic spline coefficients are computed and

stored for each of the *N* values in the table, one set of splines for

energy, another for force.  Note that these splines are different than

the ones used to pre-compute the *N* values.  Those splines were fit