README.md minor changes

onboarding/CD_newComponentTag/custom-service-java/README.md

@@ -1 +1,17 @@
-hello world
+## What is a custom service in Dynatrace?
+If your application services aren't built on standard technologies, they may not be recognized out-of-the box. 
+You can monitor these technologies, but you'll need to define them as custom services with specific service entry points. 
+Another use case for custom services are microservices that are used by a larger application that aren't exposed via communication technologies.
+
+## How to create a custom service?
+- Edit the file custom-service-java.yaml. You can use the customService1 as a template. Copy and paste it below, changing the skipDeployment to true.
+- Fill up all the remaining inputs with the details of the endpoint you're interested to monitor (className, methodName, etc...)
+
+## What if i have multiple classes?
+- Clone the template-1-1.json to a new one called template-2-1.json.
+- Edit the 2nd json adding a 2nd rule separated with a coma with the first one
+- Change the name of the {{.values}}. Make sure to add them in the YAML definition.
+
+## What if i have multiple methods?
+- Same process as before, just call it template-1-2.json
+- In this way you can extend to a custom service with n classes and k methods: template-n-k.json