updating DIRECTORY.md

Author: cclauss

DIRECTORY.md

@@ -712,6 +712,7 @@
 ## [Knapsack](knapsack)
   * [Greedy Knapsack](knapsack/greedy_knapsack.py)
   * [Knapsack](knapsack/knapsack.py)
+  * [Knapsack Graph Generation](knapsack/knapsack_graph_generation.py)
   * [Recursive Approach Knapsack](knapsack/recursive_approach_knapsack.py)
   * Tests
     * [Test Greedy Knapsack](knapsack/tests/test_greedy_knapsack.py)