docs: update README submission section and improve clarity

src/main/java/dev/banking/DemoApplication.java

@@ -13,8 +13,6 @@ import java.util.concurrent.*;
  * - Building the system
  * - Running the simulation
  * - Managing lifecycle (threads, schedulers)
- *
- * This class replaces DemoFactory as a full runner.
  */
 public final class DemoApplication {
 

src/main/java/dev/banking/Main.java

@@ -4,7 +4,6 @@ package dev.banking;
  * Entry point of the application.
  *
  * IMPORTANT:
- * - Do NOT modify this file in student assignment.
  * - This is only a wrapper for running the demo.
  */
 public final class Main {

src/main/java/dev/banking/model/Transaction.java

@@ -2,8 +2,6 @@ package dev.banking.model;
 
 /**
  * Base class for all transaction types.
- *
- * Transactions are immutable and thread-safe.
  */
 public abstract class Transaction {