add doxygen group for sizing fields

Tetrahedral_remeshing/doc/Tetrahedral_remeshing/PackageDescription.txt

@@ -7,6 +7,9 @@
 /// \defgroup PkgTetrahedralRemeshingClasses Classes
 /// \ingroup PkgTetrahedralRemeshingRef
 
+/// \defgroup PkgTetrahedralRemeshingSizing Sizing Fields
+/// \ingroup PkgTetrahedralRemeshingRef
+
 /*!
 \addtogroup PkgTetrahedralRemeshingRef
 

Tetrahedral_remeshing/include/CGAL/Adaptive_remeshing_sizing_field.h

@@ -40,6 +40,8 @@ namespace CGAL
 {
 
 /**
+ * @ingroup PkgTetrahedralRemeshingSizing
+ *
  * @class Adaptive_remeshing_sizing_field
  * @tparam Tr underlying triangulation type
  *
@@ -183,6 +185,8 @@ private:
 };//end of class Adaptive_remeshing_sizing_field
 
 /*!
+ * @ingroup PkgTetrahedralRemeshingSizing
+ *
  * @brief Create an adaptive sizing field for tetrahedral remeshing
  *
  * \relates Adaptive_remeshing_sizing_field

Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing_sizing_field.h

@@ -19,6 +19,8 @@ namespace CGAL
 {
 
 /*!
+* @ingroup PkgTetrahedralRemeshingSizing
+*
 * Sizing field virtual class, designed for tetrahedral remeshing
 * @tparam GT the geometric traits class
 */

Tetrahedral_remeshing/include/CGAL/Uniform_sizing_field.h

@@ -20,6 +20,8 @@
 namespace CGAL
 {
 /**
+ * @ingroup PkgTetrahedralRemeshingSizing
+ *
  * @class Uniform_sizing_field
  * @tparam GT the geometric traits class
  *