fixed removed import by mistake

spring-security-mvc-login/src/main/java/com/baeldung/spring/MvcConfig.java

@@ -1,6 +1,7 @@
 package com.baeldung.spring;
 
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;