Document that username and password are not used when Redis url is set

Closes gh-41231

spring-boot-project/spring-boot-docs/src/docs/asciidoc/data/nosql.adoc

@@ -55,6 +55,20 @@ You can specify custom connection details using `spring.data.redis.*` properties
 	      password: "secret"
 ----
 
+You can also specify the url of the Redis server directly.
+When setting the url, the host, port, username and password properties are ignored.
+This is shown in the following example:
+
+[source,yaml,indent=0,subs="verbatim",configprops,configblocks]
+----
+	spring:
+	  data:
+	    redis:
+	      url: "redis://user:secret@localhost:6379"
+	      database: 0
+----
+
+
 TIP: You can also register an arbitrary number of beans that implement `LettuceClientConfigurationBuilderCustomizer` for more advanced customizations.
 `ClientResources` can also be customized using `ClientResourcesBuilderCustomizer`.
 If you use Jedis, `JedisClientConfigurationBuilderCustomizer` is also available.