Update README.md

Author: jdaugherty

README.md

@@ -7,9 +7,4 @@ See [documentation](https://grails.github.io/grails-cache/) for further informat
 
 ## Branches
 
-The current master branch is for 6.0.x versions of the plugin.
-There is a 5.0.x branch for ongoing maintenance of 5.x versions of the plugin.
-There is a 3.x branch for ongoing maintenance of 3.x versions of the plugin.
-There is also a 1.x branch for on-going maintenance of 1.x versions of the plugin compatible with Grails 2.
-Please submit any pull requests to the appropriate branch.
-Changes to the 1.x branch will be merged into branches for more recent versions if appropriate.
+8.0 - Grails 7