feat: Add Sum class to calculate the sum of two floating-point numbers

Add a program that:
- Prompts the user to input two float values
- Computes and prints their sum
- Demonstrates use of `Scanner` for input and basic arithmetic with float types in Java.

Author: Someshdiwan

Section5OperatorExpression/src/Sum.java

@@ -3,9 +3,10 @@
 public class Sum {
     public static void main(String[] args) {
         Scanner input = new Scanner(System.in);
+        System.out.println("Enter a two numbers: ");
+
         float num1 = input.nextFloat();
         float num2 = input.nextFloat();
-
         float sum = num1 + num2;
 
         System.out.println("Sum = " + sum);