Document using configurers and customisers with @LoadBalanced HTTP cl…

…ient builders. Fixes gh-1407.

docs/modules/ROOT/pages/spring-cloud-commons/common-abstractions.adoc

@@ -253,6 +253,21 @@ public class MyClass {
 The URI needs to use a virtual host name (that is, a service name, not a host name).
 The `BlockingLoadBalancerClient` is used to create a full physical address.
 
+In order to leverage additional capabilities that Spring Boot provides for `RestTemplateBuilder` (for example, observability support) you may want to use the autoconfigured
+`RestTemplateBuilderConfigurer` while creating the `@LoadBalanced RestTemplateBuilder` beans:
+
+[source,java,indent=0]
+----
+@Configuration
+public class MyConfiguration {
+
+	@LoadBalanced
+	RestTemplateBuilder loadBalancedRestTemplateBuilder(RestTemplateBuilderConfigurer configurer) {
+		return configurer.configure(new RestTemplateBuilder());
+	}
+}
+----
+
 IMPORTANT: To use it, add xref:spring-cloud-commons/loadbalancer.adoc#spring-cloud-loadbalancer-starter[Spring Cloud LoadBalancer starter] to your project.
 
 [[multiple-resttemplate-builder-beans]]