added deprecation message

.gitignore

@@ -89,3 +89,4 @@ typings/
 
 # DynamoDB Local files
 .dynamodb/
+dist/index.js

README.md

@@ -6,6 +6,8 @@
   <a href="https://github.com/actions/setup-ruby/actions"><img alt="versions status" src="https://github.com/actions/setup-ruby/workflows/ruby-versions/badge.svg"></a>  
 </p>
 
+**Please note: This repository is currently unmaintained by a team of developers at GitHub, we are not going to be updating issues or pull requests on this repository. Please, migrate your workflows to [ruby/setup-ruby](https://github.com/ruby/setup-ruby) by official [Ruby community](https://www.ruby-lang.org/en/).**
+
 This action sets up a ruby environment for versions which are installed on the [Actions Virtual Environments](https://github.com/actions/virtual-environments).
 
 Virtual environments contain only one Ruby version within a 'major.minor' release, and are updated with new releases.  Hence, a workflow should only be bound to minor versions.

src/main.ts

@@ -3,6 +3,7 @@ import * as cache from './cache';
 
 export async function run() {
   try {
+    core.info('Please note: this action is deprecated and will not be maintained in future by GitHub engineers. Please, migrate to https://github.com/ruby/setup-ruby from official Ruby community.');
     let versionSpec = core.getInput('ruby-version', {required: true});
     if (!versionSpec) {
       // deprecated