add dedup comment

lab5/zad1/src/main.rs

@@ -164,6 +164,7 @@ impl Graph {
         // Return F, which specifically includes the corresponding edges in E
         forest.iter()
             .map(|i| min_edges[i.index])
+            // deduplication
             .collect::<HashSet<_>>()
             .iter()
             .map(|e| *e)