erlang/otp — reverse-engineered prompt

I want this repo turned into a working local Erlang/OTP source build that I can actually use, not just browse. Please get it building cleanly from source, make sure the runtime and shell start up, and verify everything with a tiny hello world style example that compiles and runs in the Erlang shell.

If anything is missing on the machine, add whatever setup or helper scripts make the process smooth. I would also love a simple readme update or a short getting started note that explains, in plain English, how to build it, start it, and run the sample so a beginner can follow along without knowing the codebase. If there are common gotchas or platform specific steps, call those out too.

The main goal is that someone can clone this repo, follow a small set of steps, and end up with a working Erlang/OTP install built from this source tree. Feel free to look up the current docs online if you need to.