Update documentation for new HealthIndicator support

spring-boot-docs/src/main/asciidoc/index.adoc

 = Spring Boot Reference Guide
-Phillip Webb; Dave Syer; Josh Long; Stéphane Nicoll; Rob Winch; Andy Wilkinson; Marcel Overdijk;
+Phillip Webb; Dave Syer; Josh Long; Stéphane Nicoll; Rob Winch; Andy Wilkinson; Marcel Overdijk; Christian Dupuis;
 :doctype: book
 :toc:
 :toclevels: 4

spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -162,9 +162,13 @@ To provide custom health information you can register a Spring bean that impleme
 	}
 ----
 
-Spring Boot also provides a
-{sc-spring-boot-actuator}/health/SimpleHealthIndicator.{sc-ext}[`SimpleHealthIndicator`]
-implementation that attempts a simple database test.
+Spring Boot provides a
+{sc-spring-boot-actuator}/health/SimpleDatabaseHealthIndicator.{sc-ext}[`SimpleDatabaseHealthIndicator`]
+implementation that attempts a simple database test as well as implementations for 
+Redis and MongoDB. 
+
+Spring Boot adds the `HealthIndicator` instances automatically if beans of type `DataSource`,
+`MongoTemplate` or `RedisConnectionFactory` are present in the `ApplicationContext`.