docs: add explanation for front controller (#2929)

front-controller/src/main/java/com/iluwatar/front/controller/App.java

@@ -26,7 +26,7 @@ package com.iluwatar.front.controller;
 
 /**
  * The Front Controller is a presentation tier pattern. Essentially it defines a controller that
- * handles all requests for a web site.
+ * handles all requests for a website.
  *
  * <p>The Front Controller pattern consolidates request handling through a single handler object (
  * {@link FrontController}). This object can carry out the common the behavior such as

front-controller/src/main/java/com/iluwatar/front/controller/ApplicationException.java

@@ -24,11 +24,14 @@
  */
 package com.iluwatar.front.controller;
 
+import java.io.Serial;
+
 /**
  * Custom exception type.
  */
 public class ApplicationException extends RuntimeException {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   public ApplicationException(Throwable cause) {