Add link to rails 6 example

README.md

@@ -4,6 +4,9 @@
 
 This app demonstrates Rails 7 with PostgreSQL, import maps, turbo, stimulus and hotwire, all running in Docker.
 
+**NOTE:** [There is also an example Rails 6 application working in Docker with Webpacker](https://github.com/ryanwi/rails-on-docker)
+
+
 ## Initial setup
 ```
 docker compose build