message: Hyperlink to boost concepts.
diff: @@ -942,7 +942,8 @@ class Simplex_tree {
  *
  * Inserts all vertices and edges given by a OneSkeletonGraph.
  * OneSkeletonGraph must be a model of
  - * boost::EdgeListGraph and boost::PropertyGraph.
  + * <a href="http://www.boost.org/doc/libs/1_65_1/libs/graph/doc/EdgeListGraph.html">boost::EdgeListGraph</a>
  + * and <a href="http://www.boost.org/doc/libs/1_65_1/libs/graph/doc/PropertyGraph.html">boost::PropertyGraph</a>.
  *
  * The vertex filtration value is accessible through the property tag
  * vertex_filtration_t.
  