Update README.md

Author: eregon

README.md

@@ -3,4 +3,6 @@
 These builds are only meant to be used inside GitHub Actions with
 [ruby/setup-ruby](https://github.com/ruby/setup-ruby).
 
+Please report issues to [ruby/setup-ruby](https://github.com/ruby/setup-ruby).
+
 They might not work in any other environment.