feat : onboarding 페이지 추가

Author: purin48

src/main/java/today/meevote/config/WebConfig.java

@@ -20,6 +20,7 @@ public void addInterceptors(InterceptorRegistry registry) {
         				"/api/**",
         				"/register",
         				"/login",
+						"/hello",
         				"/v3/api-docs",
         				"/swagger",
         				"/swagger-ui.html", 

src/main/java/today/meevote/controllerAdvice/ControllerAdvice.java

@@ -13,7 +13,7 @@ public class ControllerAdvice {
     @ExceptionHandler(UnauthenticatedException.class)
     public String unauthenticatedException(UnauthenticatedException e){
     	log.error("unauthenticatedException", e);
-        return "redirect:/login";
+        return "redirect:/hello";
     }
 
     @ExceptionHandler(NotFoundException.class)

src/main/java/today/meevote/domain/etc/controller/ViewController.java

@@ -56,4 +56,9 @@ public String register() {
 	public String login() {
 		return "login/login";
 	}
+
+	@GetMapping("/hello")
+	public String hello() {
+		return "login/hello";
+	}
 }