chore: add disclaimer to release drafter

Author: jdaugherty

.github/release-drafter.yml

@@ -140,6 +140,10 @@ version-resolver:
       - 'type: patch'
   default: patch
 template: |
+  ## Disclaimer: Release Created While Under Incubation
+  
+  Apache Grails is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Apache Groovy Project. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.
+  
   ## What's Changed
 
   $CHANGES