Update directory

Author: Hardvan

DIRECTORY.md

@@ -513,6 +513,7 @@
               * [SSFScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/diskscheduling/SSFScheduling.java)
             * [EDFScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/EDFScheduling.java)
             * [FCFSScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/FCFSScheduling.java)
+            * [GangScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/GangScheduling.java)
             * [HighestResponseRatioNextScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/HighestResponseRatioNextScheduling.java)
             * [JobSchedulingWithDeadline](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/JobSchedulingWithDeadline.java)
             * [LotteryScheduling](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/scheduling/LotteryScheduling.java)
@@ -1064,6 +1065,7 @@
               * [SSFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/diskscheduling/SSFSchedulingTest.java)
             * [EDFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/EDFSchedulingTest.java)
             * [FCFSSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/FCFSSchedulingTest.java)
+            * [GangSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/GangSchedulingTest.java)
             * [HighestResponseRatioNextSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/HighestResponseRatioNextSchedulingTest.java)
             * [JobSchedulingWithDeadlineTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/JobSchedulingWithDeadlineTest.java)
             * [LotterySchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/LotterySchedulingTest.java)