Add one more code-review task & new YT link

Author: andrei-punko

README.md

@@ -263,6 +263,7 @@ We can perceive materials in this folder as project backlog or "box with other s
 | GitHub Actions: workflows, coverage, badges                                                      | [YouTube](https://youtu.be/8O9ZmQfixF4) | [Repo1](https://github.com/andrei-punko/spring-boot-3-template) [Repo2](https://github.com/andrei-punko/aspectj-sandbox) [Repo3](https://github.com/andrei-punko/java-interview-coding) [Repo4](https://github.com/andrei-punko/spring-boot-jwt) |
 | Самодельный ArrayList 2                                                                          | [YouTube](https://youtu.be/VBdYvDW8WL8) | [Code](src/main/java/by/andd3dfx/collections/custom/CustomArrayList.java)                                                                                                                                                                        |
 | Ревью и рефакторинг кода подписчика (Spring Boot сервис)                                         | [YouTube](https://youtu.be/sQQ0pkR9YRM) | [Repo](https://github.com/EkaterinaBezheskaia/CaseLabTestTask)                                                                                                                                                                                   |
+| System Design: Scale from zero to millions of users (presentation)                               | [YouTube](https://youtu.be/wpif_188g1c) | -                                                                                                                                                                                                                                                |
 
 | Title                           |           YouTube video link            |
 |---------------------------------|:---------------------------------------:|

interview-materials/code-review/code-review-4.md

@@ -0,0 +1,31 @@
+# Perform review of this code
+
+How many instances of `PrototypeBean` class will be created?
+
+```java
+@Configuration
+public class AppConfig {
+
+    @Bean
+    @Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
+    public PrototypeBean prototypeBean() {
+        return new PrototypeBean();
+    }
+
+    @Bean
+    public MyService myService() {
+        return new MyService();
+    }
+}
+
+public class MyService {
+
+    @Autowired
+    private PrototypeBean prototypeBean;
+
+    public void method() {
+        prototypeBean.get();
+        prototypeBean.process();
+    }
+}
+```