Update README file

README.md

 # Pacemaker customization example
 
 This example demonstrates
-- how to create a new import pipeline
-- how to extend file resolver to observer import directory
-- how to create virtual conditions
-- how to add system configurations and default settings
-
-Please refer to [Pacemaker documentation](https://docs.met.tdintern.de/pacemaker/1.2/how-to-extend/import-processes/create-an-additional-import-process.html) for details.
+- how to overwrite an existing step
+- how to manipulate arguments of an existing pipeline