Fix @LogLevels copyright, javadoc

Author: garyrussell

spring-rabbit-junit/src/main/java/org/springframework/amqp/rabbit/junit/LogLevels.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 the original author or authors.
+ * Copyright 2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,9 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 
 /**
- * Test classes annotated with this will change logging levels between tests.
+ * Test classes annotated with this will change logging levels between tests. It can also
+ * be applied to individual test methods. If both class-level and method-level annotations
+ * are present, the method-level annotation is used.
  *
  * @author Gary Russell
  * @since 2.2