Add reference to SpringBootApplication in EnableAutoConfiguration

Closes spring-projectsgh-9521

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/EnableAutoConfiguration.java

@@ -41,18 +41,22 @@
  * {@link TomcatEmbeddedServletContainerFactory} (unless you have defined your own
  * {@link EmbeddedServletContainerFactory} bean).
  * <p>
+ * When using {@link SpringBootApplication}, the auto-configuration of the context is
+ * automatically enabled and adding this annotation has therefore no additional effect.
+ * <p>
  * Auto-configuration tries to be as intelligent as possible and will back-away as you
  * define more of your own configuration. You can always manually {@link #exclude()} any
  * configuration that you never want to apply (use {@link #excludeName()} if you don't
  * have access to them). You can also exclude them via the
  * {@code spring.autoconfigure.exclude} property. Auto-configuration is always applied
  * after user-defined beans have been registered.
  * <p>
- * The package of the class that is annotated with {@code @EnableAutoConfiguration} has
- * specific significance and is often used as a 'default'. For example, it will be used
- * when scanning for {@code @Entity} classes. It is generally recommended that you place
- * {@code @EnableAutoConfiguration} in a root package so that all sub-packages and classes
- * can be searched.
+ * The package of the class that is annotated with {@code @EnableAutoConfiguration},
+ * usually via {@code @SpringBootApplication}, has specific significance and is often used
+ * as a 'default'. For example, it will be used when scanning for {@code @Entity} classes.
+ * It is generally recommended that you place {@code @EnableAutoConfiguration} (if you're
+ * not using {@code @SpringBootApplication}) in a root package so that all sub-packages
+ * and classes can be searched.
  * <p>
  * Auto-configuration classes are regular Spring {@link Configuration} beans. They are
  * located using the {@link SpringFactoriesLoader} mechanism (keyed against this class).
@@ -66,6 +70,7 @@
  * @see ConditionalOnMissingBean
  * @see ConditionalOnClass
  * @see AutoConfigureAfter
+ * @see SpringBootApplication
  */
 @SuppressWarnings("deprecation")
 @Target(ElementType.TYPE)