Add necessary comment to MatrixMultiplication.java

Author: Nishitha0730

src/main/java/com/thealgorithms/matrix/MatrixMultiplication.java

@@ -13,11 +13,12 @@ private MatrixMultiplication() {
      * @throws IllegalArgumentException if the matrices cannot be multiplied
      */
     public static double[][] multiply(double[][] matrixA, double[][] matrixB) {
-
+        // Check the input matrices are not null
         if (matrixA == null || matrixB == null) {
             throw new IllegalArgumentException("Input matrices cannot be null");
         }
 
+        // Validate the matrix dimensions
         if (matrixA[0].length != matrixB.length) {
             throw new IllegalArgumentException("Matrices cannot be multiplied: incompatible dimensions.");
         }
@@ -26,8 +27,10 @@ public static double[][] multiply(double[][] matrixA, double[][] matrixB) {
         int colsA = matrixA[0].length;
         int colsB = matrixB[0].length;
 
+        // Initialize the result matrix with zeros
         double[][] result = new double[rowsA][colsB];
 
+        // Perform matrix multiplication
         for (int i = 0; i < rowsA; i++) {
             for (int j = 0; j < colsB; j++) {
                 for (int k = 0; k < colsA; k++) {