message: Extended the description of the example.
diff: -// ETHOS Example - Mesh optimizer
  +// MFEM Example 17
  //
  // Compile with: make exsm
  //
  // exsm -o 2 -rs 0 -ji 0.0 -mid 2 -tid 1 -lim -lc 0.001 -ni 10 -ls 1 -bnd
  //
  // Description:
  -// This example code performs mesh optimization using Target-matrix
  -// optimization paradigm coupled with Variational Minimization. The smoother
  -// is based on a combination of target element and quality metric that the
  -// users chooses, which in-turn determines which features of the mesh - size,
  -// quality and/or orientation - are optimized.
  -
  +// This example performs mesh optimization using the Target-Matrix
  +// Optimization Paradigm (TMOP), and a global variational minimization
  +// approach. It minimizes the quantity sum_T int_T mu(Jtr(x)), where T are
  +// the target (ideal) elements, Jtr is the Jacobian of the transformation
  +// from the reference to the target element, and mu is the mesh quality
  +// metric. This metric can measure shape, size or alignment of the region
  +// around each quadrature point. The combination of targets and quality
  +// metrics is used to optimize the physical node positions, i.e., they must
  +// be as close as possible to the shape/size/alignment of their targets.
  +//
  +// This example also demonstrates a possible use of nonlinear operators (the
  +// class HyperelasticModel defining mu(Jtr), and HyperelasticNLFIntegrator
  +// defining int mu(Jtr)), as well as their coupling to Newton methods for
  +// solving minimization problems. Note that the utilized Newton methods are
  +// oriented towards avoiding negative mesh Jacobian determinants. Each Newton
  +// step requires the inversion of a Jacobian matrix, which is done through an
  +// inner linear solver.
  #include "mfem.hpp"
  