Update DIRECTORY.md

Author: NithinU2802

DIRECTORY.md

@@ -744,6 +744,7 @@
           - 📄 [Rotation](src/main/java/com/thealgorithms/strings/Rotation.java)
           - 📄 [StringCompression](src/main/java/com/thealgorithms/strings/StringCompression.java)
           - 📄 [StringMatchFiniteAutomata](src/main/java/com/thealgorithms/strings/StringMatchFiniteAutomata.java)
+          - 📄 [SuffixArray](src/main/java/com/thealgorithms/strings/SuffixArray.java)
           - 📄 [Upper](src/main/java/com/thealgorithms/strings/Upper.java)
           - 📄 [ValidParentheses](src/main/java/com/thealgorithms/strings/ValidParentheses.java)
           - 📄 [WordLadder](src/main/java/com/thealgorithms/strings/WordLadder.java)
@@ -1413,6 +1414,7 @@
           - 📄 [RotationTest](src/test/java/com/thealgorithms/strings/RotationTest.java)
           - 📄 [StringCompressionTest](src/test/java/com/thealgorithms/strings/StringCompressionTest.java)
           - 📄 [StringMatchFiniteAutomataTest](src/test/java/com/thealgorithms/strings/StringMatchFiniteAutomataTest.java)
+          - 📄 [SuffixArrayTest](src/test/java/com/thealgorithms/strings/SuffixArrayTest.java)
           - 📄 [UpperTest](src/test/java/com/thealgorithms/strings/UpperTest.java)
           - 📄 [ValidParenthesesTest](src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java)
           - 📄 [WordLadderTest](src/test/java/com/thealgorithms/strings/WordLadderTest.java)