tweak docs for dump_modify units command some more

example of ones that do are the "granular pair styles"_pair_gran.html

which calculate the tangential force between two particles and return

its components and magnitude acting on atom I for N = 1,2,3,4.  See

individual pair styles for details. When using pair style {hybrid},

the output will be that of the Nth quantity from the active sub-style

active or 0.0. The maximum allowed N is the maximum of any sub-style.

When using pair style {hybrid/overlay} all additional properties of

all pair styles are available for output, but the values of inactive

sub-styles for a given pair of atom types will be 0.0. Thus if there

are, for example, 3 sub-styles and 2 of them have additional output

(3 and 4 items, respectively), the maximum N would be 7 and {p1}, {p2},

and {p3} would refer to the first 3 additional properties and the

remaining allowed parameters {p4} to {p7} would address properties {p1}

to {p4} of the second sub-style with additional properties.

individual pair styles for details.

When using {pN} with pair style {hybrid}, the output will be the Nth

quantity from the sub-style that computes the pairwise interaction

(based on atom types).  If that sub-style does not define a {pN},

the output will be 0.0.  The maximum allowed N is the maximum number

of quantities provided by any sub-style.

When using {pN} with pair style {hybrid/overlay} the quantities

from all sub-styles that provide them are concatenated together

into one long list. For example, if there are 3 sub-styles and

2 of them have additional output (with 3 and 4 quantities,

respectively), then 7 values ({p1} up to {p7}) are defined.

The values {p1} to {p3} refer to quantities defined by the first

of the two sub-styles.  Values {p4} to {p7} refer to quantities

from the second of the two sub-styles.  If the referenced {pN}

is not computed for the specific pairwise interaction (based on

atom types), then the output will be 0.0.

The value {dist} will be in distance "units"_units.html.  The value

{eng} will be in energy "units"_units.html.  The values {force}, {fx},