integrate fix rhok into the LAMMPS source code management and documentation system

doc/src/Section_commands.txt

@@ -728,6 +728,7 @@ package"_Section_start.html#start_3.
 "qtb"_fix_qtb.html,
 "reax/c/bonds"_fix_reax_bonds.html,
 "reax/c/species"_fix_reaxc_species.html,
+"rhok"_fix_rhok.html,
 "rx"_fix_rx.html,
 "saed/vtk"_fix_saed_vtk.html,
 "shardlow"_fix_shardlow.html,

doc/src/fixes.txt

@@ -124,6 +124,7 @@ Fixes :h1
    fix_reaxc_species
    fix_recenter
    fix_restrain
+   fix_rhok
    fix_rigid
    fix_rx
    fix_saed_vtk

doc/src/lammps.book

@@ -253,6 +253,7 @@ fix_reaxc_species.html
 fix_recenter.html
 fix_restrain.html
 fix_rigid.html
+fix_rhok.html
 fix_rx.html
 fix_saed_vtk.html
 fix_setforce.html

src/.gitignore

@@ -503,6 +503,8 @@
 /fix_reaxc_bonds.h
 /fix_reaxc_species.cpp
 /fix_reaxc_species.h
+/fix_rhok.cpp
+/fix_rhok.h
 /fix_rigid.cpp
 /fix_rigid.h
 /fix_rigid_nh.cpp