feat: Add demo output for makeItACombo in Meal class

WHAT the code does:
- Defines a `Meal` class with attributes `name` and `cost`.
- Constructor initializes the meal with a food name and price.
- `makeItACombo()` upgrades a meal to a combo by:
  - Adding ₹50.0 to cost.
  - Appending `" Combo"` to the name.
- `getBill()` returns the final bill amount.
- Overrides `toString()` for formatted string output.
- `main()` tests functionality by:
  1. Printing initial meal.
  2. Applying `makeItACombo()` and printing updated meal with a label.
  3. Printing final bill.

WHY this matters:
- Demonstrates how to model **real-world objects** with Java classes.
- Highlights method-driven state change (combo upgrade).
- Shows usage of `toString()` for human-readable output.
- Reinforces the principle of encapsulation with private fields.

HOW it works:
1. `Meal m1 = new Meal("Burger", 120)` → creates meal.
2. `System.out.println(m1)` → invokes `toString()`.
3. `m1.makeItACombo()` → cost increases to ₹170, name becomes `"Burger Combo"`.
4. Prints `"makeItAComboBurger Combo costs ₹170.0"`.
5. `getBill()` → returns final cost `170.0`.

Tips & gotchas:
- Each call to `makeItACombo()` keeps stacking ₹50 → may not be desired.
- Hardcoded ₹50 could be replaced with a configurable combo charge.
- For money, prefer `BigDecimal` to avoid floating-point inaccuracies.
- `System.out.println("makeItACombo"+m1);` concatenates label directly with meal info — spacing could be improved for clarity.

Use-cases:
- Educational Java OOP practice.
- Simulating POS (Point of Sale) billing systems.
- Starter example for **mutable object state**.
- Base for extending features like discounts, taxes, or menus.

Short key: class-meal-combo-upgrade-demo

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section10Methods/Methods 2.O/src/Meal.java

@@ -1,18 +1,38 @@
-public class Meal
-{
-    //Instance attributes//
+public class Meal {
+    // Instance attributes
     private String name;
     private double cost;
 
-    //Class constructor//
-    public Meal(String food, double price)
-    {
-        name = food;
-        cost = price;
+    // Class constructor
+    public Meal(String food, double price) {
+        this.name = food;
+        this.cost = price;
     }
 
-    //Instance methods//
-    /* Complete the method makeItACombo */
-}
+    // Instance method: upgrade meal to combo (adds fixed extra cost)
+    public void makeItACombo() {
+        // Let's say making it a combo adds ₹50.0
+        this.cost += 50.0;
+        this.name += " Combo";
+    }
 
-/* Complete the method getBill */
+    // Instance method: return bill amount
+    public double getBill() {
+        return this.cost;
+    }
+
+    // toString method for display
+    @Override
+    public String toString() {
+        return name + " costs ₹" + cost;
+    }
+    public static void main(String[] args) {
+        Meal m1 = new Meal("Burger", 120);
+        System.out.println(m1);
+
+        m1.makeItACombo();
+        System.out.println("makeItACombo"+m1);
+
+        System.out.println("Bill: ₹" + m1.getBill());
+    }
+}