Update readme

README.md

@@ -11,14 +11,17 @@ See https://github.com/heroku/docker-heroku-ruby-builder#building-with-github-ac
 Make sure you've generated a docker image:
 
 ```
-bundle exec rake "generate_image[heroku-22]"
+bin/activate_docker heroku-24
 ```
 
 Then run the following:
 
 ```
-bundle exec rake "new[9.3.0.0,heroku-22]" &&
-bash rubies/heroku-22/jruby-9.3.0.0.sh &&
-bundle exec rake "upload[9.3.0.0,heroku-22]" &&
-echo "Done building jruby 9.3.0.0 for heroku-22"
+bin/build_jruby heroku-24 9.4.7.0
+```
+
+This will generate tar files in the `builds` folder. You can exercise them by running:
+
+```
+bin/print_summary heroku-24 9.4.7.0
 ```