DATAMONGO-2586 - Add support for reactive auditing.

We now provide a fully reactive variant for auditing with EnableReactiveMongoAuditing.

Original Pull Request: #877

src/main/asciidoc/new-features.adoc

@@ -1,6 +1,11 @@
 [[new-features]]
 = New & Noteworthy
 
+[[new-features.3.1]]
+== What's New in Spring Data MongoDB 3.1
+
+* <<mongo.auditing,Reactive auditing>> enabled through `@EnableReactiveMongoAuditing`. `@EnableMongoAuditing` no longer registers `ReactiveAuditingEntityCallback`.
+
 [[new-features.3.0]]
 == What's New in Spring Data MongoDB 3.0
 

src/main/asciidoc/reference/mongo-auditing.adoc

@@ -30,3 +30,22 @@ To activate auditing functionality via XML, add the Spring Data Mongo `auditing`
 ----
 ====
 
+If you wish to use auditing with the reactive programming model, then enable auditing through `@EnableReactiveMongoAuditing`
+
+.Activating auditing using JavaConfig
+====
+[source,java]
+----
+@Configuration
+@EnableReactiveMongoAuditing
+class Config {
+
+  @Bean
+  public ReactiveAuditorAware<AuditableUser> myAuditorProvider() {
+      return new AuditorAwareImpl();
+  }
+}
+----
+====
+If you expose a bean of type `ReactiveAuditorAware` to the `ApplicationContext`, the auditing infrastructure picks it up automatically and uses it to determine the current user to be set on domain types. If you have multiple implementations registered in the `ApplicationContext`, you can select the one to be used by explicitly setting the `auditorAwareRef` attribute of `@EnableReactiveMongoAuditing`.
+