couple more doc page tweaks

doc/src/Intro_overview.txt

@@ -14,9 +14,8 @@ ensembles of particles in a liquid, solid, or gaseous state.  It can
 model atomic, polymeric, biological, solid-state (metals, ceramics,
 oxides), granular, coarse-grained, or macroscopic systems using a
 variety of interatomic potentials (force fields) and boundary
-conditions.  The majority of these models are for materials of various
-kinds.  It can model 2d or 3d systems with only a few particles up to
-millions or billions.
+conditions.  It can model 2d or 3d systems with only a few particles
+up to millions or billions.
 
 LAMMPS can be built and run on a laptop or destop machine, but is
 designed for parallel computers.  It will run on any parallel machine

doc/src/Manual.txt

@@ -28,13 +28,13 @@ LAMMPS Documentation :c,h1
 LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel
 Simulator.
 
-LAMMPS is a classical molecular dynamics simulation code designed to
-run efficiently on parallel computers.  It is primarily used for
-materials modeling of various kinds.  It was developed originally at
-Sandia National Laboratories, a US Department of Energy facility.  The
-majority of funding for LAMMPS has come from the US Department of
-Energy (DOE).  LAMMPS is an open-source code, distributed freely under
-the terms of the GNU Public License (GPL).
+LAMMPS is a classical molecular dynamics simulation code with a focus
+on materials modeling.  It was designed to run efficiently on parallel
+computers.  It was developed originally at Sandia National
+Laboratories, a US Department of Energy facility.  The majority of
+funding for LAMMPS has come from the US Department of Energy (DOE).
+LAMMPS is an open-source code, distributed freely under the terms of
+the GNU Public License (GPL).
 
 The "LAMMPS website"_lws has a variety of information about the code.
 It includes links to an on-line version of this manual, a "mail