Update README.md for 5.0.0 release

Author: jamesfredley

README.md

@@ -4,6 +4,8 @@
 
 ## Branches
 
+**5.0.x** Version of the plugin compatible with Grails 6 and Liquibase 4.19
+
 **4.0.x** Version of the plugin compatible with Grails 5 and Liquibase 4.6
 
 **3.x** Version of the plugin compatible with Grails 3 / 4 and Hibernate 5.
@@ -28,13 +30,15 @@ One popular approach is to have a root changelog named changlog.groovy (or chang
 * 2.x: Grails 3 with Hibernate 4
 * 3.x: Grails 3 with Hibernate 5
 * 4.0.x Grails 5
+* 5.0.x Grails 6
 
 ## Documentation
 * Latest https://grails.github.io/grails-database-migration/latest/
 * Grails 2: https://grails.github.io/grails-database-migration/docs/manual/index.html
 * Grails 3 (Hibernate 4): https://grails.github.io/grails-database-migration/2.0.x/index.html
 * Grails 3/4 (Hibernate 5): https://grails.github.io/grails-database-migration/3.0.x/index.html
 * Grails 5 (Hibernate 5): https://grails.github.io/grails-database-migration/4.0.x/index.html
+* Grails 6 (Hibernate 5): https://grails.github.io/grails-database-migration/5.0.x/index.html
 * Snapshot: https://grails.github.io/grails-database-migration/snapshot/index.html