message: Add some documentation in two-pass source file
diff: //
  // SPDX-License-Identifier: (BSD-3-Clause)
  +/*! \file spin_bvh_two_pass.cpp
  + * \brief This example code demonstrates the device kernel query capabilities
  + * of the BVH class in Axom's spin component.
  + *
  + * This file shows how to run customized traversal queries on a bounding volume
  + * hierarchy with a device kernel-copyable object, by demonstrating its use to
  + * generate a set of candidate mesh self-intersections.
  + */
  +
  // Axom includes
  #include "axom/core.hpp"
  #include "axom/mint.hpp"
  @@ -65,6 +74,28 @@ void finalize_logger()
  slic::finalize();
  }
  +/*!
  + * \brief Runs the "broad-phase" part of a collision detection query on a mesh.
  + *
  + * In most implementations of collision detection, the search is divided into
  + * two separate phases: a "broad phase" which utilizes a fast-but-conservative
  + * collision test to quickly prune the search space of potential collisions,
  + * followed by a "narrow phase" which uses a more accurate collision test on
  + * the remaining candidate collisions.
  + *
  + * The below implements the broad-phase query with a bounding volume hierarchy
  + * of bounding boxes constructed from the input mesh's zones, and returns an
  + * output of potentially-intersecting mesh elements as pairs of indices.
  + *
  + * The subsequent narrow-phase implementation can then be run on the returned
  + * pairs of indices. What constitutes depends on the mesh elements; for
  + * example, triangle-triangle tests if run on a triangle surface mesh, or
  + * polyhedral intersection tests for a mesh of arbitrary polyhedral zones.
  + *
  + * \param [in] mesh the input mesh
  + * \param [out] firstPair first index of pairs of potentially colliding zones
  + * \param [out] secondPair second index of pairs of potentially colliding zones
  + */
  template <typename ExecSpace>
  void find_collisions_broadphase(const mint::Mesh* mesh,
  axom::Array<IndexType>& firstPair,
  @@ -212,7 +243,8 @@ struct Arguments
  ->check(axom::CLI::ExistingFile)
  ->required();
  - std::string pol_info = "Sets execution space of the .\n";
  + std::string pol_info =
  + "Sets execution space of the BVH two-pass example.\n";
  pol_info += "Set to \'seq\' to use sequential execution policy.";
  #ifdef AXOM_USE_OPENMP
  pol_info += "\nSet to \'omp\' to use an OpenMP execution policy.";
  