integrate compute pentropy/atom into the documentation tree

doc/src/Section_commands.txt

@@ -861,6 +861,7 @@ package"_Section_start.html#start_3.
 "meso/t/atom"_compute_meso_t_atom.html,
 "pe/tally"_compute_tally.html,
 "pe/mol/tally"_compute_tally.html,
+"pentropy/atom"_compute_pentropy_atom.html,
 "pressure/uef"_compute_pressure_uef.html,
 "saed"_compute_saed.html,
 "smd/contact/radius"_compute_smd_contact_radius.html,

doc/src/computes.txt

@@ -63,6 +63,7 @@ Computes :h1
    compute_pair_local
    compute_pe
    compute_pe_atom
+   compute_pentropy_atom
    compute_plasticity_atom
    compute_pressure
    compute_pressure_uef

doc/src/lammps.book

@@ -347,6 +347,7 @@ compute_pair.html
 compute_pair_local.html
 compute_pe.html
 compute_pe_atom.html
+compute_pentropy_atom.html
 compute_plasticity_atom.html
 compute_pressure.html
 compute_pressure_uef.html