updating DIRECTORY.md

Author: cclauss

DIRECTORY.md

@@ -642,9 +642,9 @@
   * [Graphs Floyd Warshall](graphs/graphs_floyd_warshall.py)
   * [Greedy Best First](graphs/greedy_best_first.py)
   * [Greedy Min Vertex Cover](graphs/greedy_min_vertex_cover.py)
-  * [Johnson Graph](graphs/johnson_graph.py)
   * [Hopcroft Karp](graphs/hopcroft_karp.py)
   * [Johnson](graphs/johnson.py)
+  * [Johnson Graph](graphs/johnson_graph.py)
   * [Kahns Algorithm Long](graphs/kahns_algorithm_long.py)
   * [Kahns Algorithm Topo](graphs/kahns_algorithm_topo.py)
   * [Karger](graphs/karger.py)