documentation

The controller program can exit due to many errors. There is a way to handle restart of the program.

```bash
# install nodejs which also installs npm package manager
npm install -g pm2
pm2 start controller-1.py --interpreter .venv/bin/python --restart-delay=60000 --log controller-1.log
```

This command uses virtual environment and executes `controller-1.py`. If it exits for any reason, it gets restarted after 60 seconds. The output and error logs of the `controller-1.py` get stored in `controller-1.log`.

The issue names controller-1.py, the .venv/bin/python interpreter, PM2, and controller-1.log, but no documentation file or entry point. First locate the project's documentation or README and determine where controller startup instructions belong. Done means documenting the PM2 installation and restart command accurately, including the 60-second delay and log location.

Written by the indexing model from the issue text.