Add examples for do..while and foreach loops in programming book

main.typ

@@ -317,7 +317,25 @@ while (shouldQuit) {
   }
 }
 
-//TODO: do..while example & foreach example
+string correctPin = "1234";
+string enteredPin = "";
+
+do {
+  Console.Write("Please provide your PIN: ");
+  enteredPin = Console.ReadLine();
+
+  if (enteredPin != correctPin) {
+    Console.WriteLine("Incorrect PIN. Try again");
+  }
+} while (enteredPin != correctPin);
+
+Console.WriteLine("Correct PIN! Access granted.");
+
+string[] shoppingList = new string[] { "bread", "chicken", "butter"};
+Console.WriteLine("Your shopping list:");
+foreach (string product in shoppingList) {
+  Console.WriteLine($"- {product}");
+}
 ```
 ==== Rezultat
 ==== Wyjaśnienie