Add reference to Infinispan starter

Closes gh-8592

Author: snicoll

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

@@ -4192,6 +4192,13 @@ Infinispan has no default configuration file location so it must be specified ex
 Caches can be created on startup via the `spring.cache.cache-names` property. If a custom
 `ConfigurationBuilder` bean is defined, it is used to customize them.
 
+[NOTE]
+====
+The support of Infinispan in Spring Boot is restricted to the embedded mode and is quite
+basic. If you want more options you should use the official Infinispan Spring Boot starter
+instead, check
+https://github.com/infinispan/infinispan-spring-boot[the documentation] for more details.
+====
 
 
 [[boot-features-caching-provider-couchbase]]

spring-boot-samples/spring-boot-sample-cache/README.adoc

@@ -92,7 +92,9 @@ can set the `spring.cache.infinispan.config` property to use the provided
 TIP: Run sample cache application using Infinispan with
 `$mvn spring-boot:run -Pinfinispan`.
 
-
+NOTE: If you want to use the client/server mode or if you need more options, Infinispan
+provides an official Spring Boot starter, check
+https://github.com/infinispan/infinispan-spring-boot[the documentation] for more details.
 
 === Couchbase
 Add the `java-client` and `couchbase-spring-cache` dependencies and make sure that