Merge pull request #5930 from drwells/fix-unsigned-char

Use types::boundary_id in a code sample.

diff --cc examples/step-38/doc/results.dox
index 06b9bb82033e2e297861f5ba48863e3996636e7c,6bc5fbc2e4620b3422985c7337c26bb706237b76..51b3e2d3f6a747a4f52bda3e9b500615d4c10490
--- 1/examples/step-38/doc/results.dox
--- 2/examples/step-38/doc/results.dox
+++ b/examples/step-38/doc/results.dox
@@@ -119,10 -119,10 +119,10 @@@ void LaplaceBeltrami<spacedim>::make_gr
      Triangulation<spacedim> volume_mesh;
      GridGenerator::half_hyper_ball(volume_mesh);
  
 -    volume_mesh.set_boundary (0, boundary_description);
 +    volume_mesh.set_manifold (0, boundary_description);
      volume_mesh.refine_global (4);
  
-     std::set<unsigned char> boundary_ids;
+     std::set<types::boundary_id> boundary_ids;
      boundary_ids.insert (0);
  
      GridGenerator::extract_boundary_mesh (volume_mesh, triangulation,