Update DIRECTORY.md

Author: DenizAltunkapan

DIRECTORY.md

@@ -761,6 +761,7 @@
           - 📄 [SelectionSortRecursive](src/main/java/com/thealgorithms/sorts/SelectionSortRecursive.java)
           - 📄 [ShellSort](src/main/java/com/thealgorithms/sorts/ShellSort.java)
           - 📄 [SlowSort](src/main/java/com/thealgorithms/sorts/SlowSort.java)
+          - 📄 [SmoothSort](src/main/java/com/thealgorithms/sorts/SmoothSort.java)
           - 📄 [SortAlgorithm](src/main/java/com/thealgorithms/sorts/SortAlgorithm.java)
           - 📄 [SortUtils](src/main/java/com/thealgorithms/sorts/SortUtils.java)
           - 📄 [SortUtilsRandomGenerator](src/main/java/com/thealgorithms/sorts/SortUtilsRandomGenerator.java)
@@ -1539,6 +1540,7 @@
           - 📄 [SelectionSortTest](src/test/java/com/thealgorithms/sorts/SelectionSortTest.java)
           - 📄 [ShellSortTest](src/test/java/com/thealgorithms/sorts/ShellSortTest.java)
           - 📄 [SlowSortTest](src/test/java/com/thealgorithms/sorts/SlowSortTest.java)
+          - 📄 [SmoothSortTest](src/test/java/com/thealgorithms/sorts/SmoothSortTest.java)
           - 📄 [SortUtilsRandomGeneratorTest](src/test/java/com/thealgorithms/sorts/SortUtilsRandomGeneratorTest.java)
           - 📄 [SortUtilsTest](src/test/java/com/thealgorithms/sorts/SortUtilsTest.java)
           - 📄 [SortingAlgorithmTest](src/test/java/com/thealgorithms/sorts/SortingAlgorithmTest.java)