Fix packages and annotations used in sample

Fixup accidental error in previous commit.

spring-boot-samples/spring-boot-sample-servlet/src/main/java/sample/servlet/SampleServletApplication.java

@@ -25,13 +25,13 @@ import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 
 import org.springframework.boot.SpringApplication;
-import org.springframework.boot.SpringBootConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.builder.SpringApplicationBuilder;
 import org.springframework.boot.context.web.SpringBootServletInitializer;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 
-@SpringBootConfiguration
+@Configuration
 @EnableAutoConfiguration
 public class SampleServletApplication extends SpringBootServletInitializer {