cleanup the ref manual

Constrained_triangulation_3/doc/Constrained_triangulation_3/PackageDescription.txt

@@ -7,7 +7,7 @@
 \defgroup PkgCT_3Functions Function Templates
 \ingroup PkgCT_3Ref
 
-\defgroup PkgCT_3Classes Classes
+\defgroup PkgCT_3Classes Class Templates
 \ingroup PkgCT_3Ref
 
 \addtogroup PkgCT_3Ref
@@ -34,6 +34,14 @@
 \cgalPkgDescriptionEnd
 
 \cgalClassifedRefPages
+`CGAL::make_constrained_Delaunay_triangulation_3()` is the main function to create
+a constrained Delaunay triangulation in 3D.
+The type alias `CGAL::default_constrained_triangulation_3_t<Kernel>` is the default
+constrained triangulation class.
+
+\cgalCRPSection{Functions Templates}
+
+- `CGAL::make_constrained_Delaunay_triangulation_3()`
 
 \cgalCRPSection{Concepts}
 
@@ -41,12 +49,9 @@
 - `ConstrainedDelaunayTriangulationVertexBase_3`
 - `ConstrainedDelaunayTriangulationCellBase_3`
 
-\cgalCRPSection{Functions Templates}
-
-- `CGAL::make_constrained_Delaunay_triangulation_3()`
-
-\cgalCRPSubsection{Classes}
+\cgalCRPSubsection{Class Templates}
 
+- `CGAL::Default_constrained_triangulation_3`
 - `CGAL::Constrained_Delaunay_triangulation_vertex_base_3`
 - `CGAL::Constrained_Delaunay_triangulation_cell_base_3`
 */

Constrained_triangulation_3/examples/Constrained_triangulation_3/constrained_Delaunay_triangulation_3.cpp

@@ -1,5 +1,6 @@
 #include <CGAL/make_constrained_Delaunay_triangulation_3.h>
 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Surface_mesh.h>
 #include <CGAL/draw_triangulation_3.h>
 
 #include <algorithm>

Constrained_triangulation_3/include/CGAL/make_constrained_Delaunay_triangulation_3.h

@@ -42,6 +42,8 @@ namespace CGAL {
  * \tparam Geom_traits a geometric traits class.
  *
  * \return `type` is the default 3D constrained Delaunay triangulation type.
+ *
+ * \sa default_constrained_triangulation_3_t
 */
 template <typename Geom_traits>
 struct Default_constrained_triangulation_3 {
@@ -54,11 +56,12 @@ struct Default_constrained_triangulation_3 {
 /*!
  * \ingroup PkgCT_3Classes
  * \brief The default 3D constrained Delaunay triangulation type.
- * \relates Default_constrained_triangulation_3
  * \tparam Geom_traits a geometric traits class.
  *
  * This alias template names the default 3D constrained Delaunay triangulation
  * type for a given geometric traits class.
+ *
+ * \sa Default_constrained_triangulation_3
  */
 template <typename Geom_traits>
 using default_constrained_triangulation_3_t =