Adding example on how to create a custom Target service

spring-cloud-app-broker-docs/src/docs/asciidoc/service-instances.adoc

@@ -212,6 +212,54 @@ If you use the `SpacePerServiceInstance` target, App Broker will deploy backing
 
 If you use the `ServiceInstanceGuidSuffix` target, App Broker will deploy backing applications using a unique name and hostname that incorporates the service instance GUID provided by the platform at service instance create time. For Cloud Foundry, the target location will be the org named by `spring.cloud.appbroker.deployer.cloudfoundry.default-org`, the space named by `spring.cloud.appbroker.deployer.cloudfoundry.default-space`, and an application name as `[APP-NAME]-[SI-GUID]`, where `[APP-NAME]` is the `name` listed for the application under `spring.cloud.appbroker.services.apps` and `[SI-GUID]` is the service instance GUID. The application will also use a hostname incorporating the service instance GUID as a suffix, as `[APP-NAME]-[SI-GUID]`.
 
+====== Creating a custom Target
+
+If you want to create a custom Target, app broker provides a flexible way to add new targets by just creating a new `Bean` that extends from `TargetFactory` and implementing the `create` method:
+
+[source,java]
+----
+public class CustomSpaceTarget extends TargetFactory<CustomSpaceTarget.Config> {
+
+	public CustomSpaceTarget() {
+		super(Config.class);
+	}
+
+	@Override
+	public Target create(Config config) {
+		return this::apply;
+	}
+
+	private ArtifactDetails apply(Map<String, String> properties, String name, String serviceInstanceId) {
+		String space = "my-custom-space";
+		properties.put(DeploymentProperties.TARGET_PROPERTY_KEY, space);
+
+		return ArtifactDetails.builder()
+			.name(name)
+			.properties(properties)
+			.build();
+	}
+
+	public static class Config {
+	}
+
+}
+----
+
+Once configured, we can specify in our service the new custom Target:
+
+[source, yml, indent=0]
+----
+spring:
+  cloud:
+    appbroker:
+      services:
+        - service-name: example
+          plan-name: standard
+          target:
+            name: CustomSpaceTarget
+----
+
+
 ===== Service Instance Parameters
 
 When a user provides parameters while creating or updating a service instance, App Broker can transform these parameters into details of the backing app deployment using parameters transformers. You can configure parameters transformers using properties under `parameters-transformers`, as in the following example: