#954 Improve comments.

Sources/Geometry/Interfaces/Instances/Volume.cpp

@@ -22,9 +22,10 @@ namespace HappyHeart
         
         
         /*!
-         * \brief Add a new volume to a mesh, and increment accordingly NvolumePerMesh().
+         * \brief Add a new volume to a mesh, and increment accordingly Nvolume_per_mesh.
          *
          * \param[in] mesh_identifier Identifier of the mesh to which the Volume is added.
+         * \param[in,out] Nvolume_per_mesh Number of volumes per mesh (represented by its identifier).
          *
          * \return Index of the newly added volume. This index is 0 for first volume, then 1, and so forth...
          */