README.me - please add instructions to "compile" a simple app

Please add to your readme how someone uses this framework to bundle the simplest app possible. The majority of people coming to this github project are looking for this.

More appropriately, perhaps the readme should be updated to reflect what seems to have been a perfectly reasonable decision to stop maintaining PyOxidizer

https://gregoryszorc.com/blog/2024/03/17/my-shifting-open-source-priorities/