Update functional_graph_processor.hpp

library/graphs/functional_graph_processor.hpp

@@ -7,7 +7,7 @@
 //!   int root = cycle[cyc_id][cyc_pos];
 //!   bool is_on_cycle = (v == root);
 //! @endcode
-//! root = first reachable node on cycle
+//! root = first reachable node on cycle from v
 //! t[v].childs = forest of reversed edges not in cycles
 //! @time O(n)
 //! @space O(n)