Add transformer app for function sample

function-samples/transform-user-clicks-per-region/README.adoc

@@ -0,0 +1,14 @@
+# Logger sink that logs the output from the user clicks per region Kafka Streams application's output
+
+This sink application is a modification of out-of-the-box `log` application.
+
+
+To build this application:
+
+./mvnw clean package
+
+To register this application from Spring Cloud Data Flow shell:
+
+```
+dataflow:> app register --name log-user-clicks-per-region --type app --uri file://<local parent directory of this git repo>/spring-cloud-dataflow-samples/kafka-samples/kstreams-log-user-clicks-per-region/target/kstreams-log-user-clicks-per-region-1.0.0.BUILD-SNAPSHOT.jar
+```