Add reminder to use ruby/setup-ruby@v1 for latest Ruby releases

index.js

@@ -129,6 +129,7 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
     } else {
       throw new Error(`Unknown version ${parsedVersion} for ${engine} on ${platform}
         available versions for ${engine} on ${platform}: ${engineVersions.join(', ')}
+        Make sure you use the latest version of the action with - uses: ruby/setup-ruby@v1
         File an issue at https://github.com/ruby/setup-ruby/issues if would like support for a new version`)
     }
   }