Update README.md

Author: robertoschwald

README.md

@@ -4,7 +4,7 @@
 
 The Audit Logging plugin for Grails adds generic event based Audit Logging to a Grails project.
 
-The master branch holds the codebase for plugin version 3.0.x (Grails 3.3.x).
+The master branch holds the codebase for plugin version 4.0.x (Grails 4.0.x).
 
 We currently work on a Grails 4.x branch using a new approach. See [feature/4.0.0_wip](https://github.com/robertoschwald/grails-audit-logging-plugin/tree/feature/4.0.0_wip)