format: adding author

Author: Rosander0

src/main/java/com/thealgorithms/strings/LongestCommonSubstring.java

@@ -4,6 +4,8 @@
  * Longest Common Substring finds the longest string that is a
  * contiguous substring of two input strings.
  * Example: "abcdef" and "zcdemf" -> "cde"
+ * 
+ * author: Vraj Prajapati @Rosander0
  */
 public final class LongestCommonSubstring {
 

src/test/java/com/thealgorithms/strings/LongestCommonSubstringTest.java

@@ -1,5 +1,5 @@
 package com.thealgorithms.strings;
-
+//author: Vraj Prajapati @Rosander0
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import org.junit.jupiter.api.Test;