Fix #3712: document that graphify path defaults to a directed search

(cherry picked from commit ce99295541)

graphify/__main__.py

@@ -744,6 +744,9 @@ def _run_cli() -> None:
         print("    --purge                 also delete graphify-out/ directory")
         print("  path \"A\" \"B\"            shortest path between two nodes in graph.json")
         print("    --graph <path>          path to graph.json (default graphify-out/graph.json)")
+        print("    --directed              force a directed search (the default;")
+        print("                            the JSON 'directed' flag is NOT consulted)")
+        print("    --undirected            ignore edge direction")
         print("  explain \"X\"             plain-language explanation of a node and its neighbors")
         print("    --graph <path>          path to graph.json (default graphify-out/graph.json)")
         print("  diagnose multigraph    report same-endpoint edge collapse risk in graph.json")