Improve documentation: note that repeated edges in 'insertEdges' mean…

…s overlapping boundaries

CDT/include/CDT.h

@@ -120,6 +120,10 @@ class CDT_EXPORT Triangulation
     void insertVertices(const std::vector<V2d<T> >& vertices);
     /**
      * Insert constraints (custom-type fixed edges) into triangulation
+     * @note If some edge appears more than once in @ref insertEdges input this
+     * means that multiple boundaries overlap at the edge and impacts
+     * how hole detection algorithm of @ref eraseOuterTrianglesAndHoles works.
+     * <b>Make sure there are no erroneous duplicates.</b>
      * @tparam TEdgeIter iterator that dereferences to custom edge type
      * @tparam TGetEdgeVertexStart function object getting start vertex index
      * from an edge.
@@ -140,7 +144,13 @@ class CDT_EXPORT Triangulation
         TEdgeIter last,
         TGetEdgeVertexStart getStart,
         TGetEdgeVertexEnd getEnd);
-    /// Insert constraints (fixed edges) into triangulation
+    /**
+     * Insert constraints (fixed edges) into triangulation
+     * @note If some edge appears more than once in @ref insertEdges input this
+     * means that multiple boundaries overlap at the edge and impacts
+     * how hole detection algorithm of @ref eraseOuterTrianglesAndHoles works.
+     * <b>Make sure there are no erroneous duplicates.</b>
+     */
     void insertEdges(const std::vector<Edge>& edges);
     /**
      * Erase triangles adjacent to super triangle