### What do you see as an issue?

The documentation for zombie tasks https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/tasks.html#zombie-undead-tasks is a bit abstract at the moment. There is a scope for enhancing the document by explaining how Airflow detects tasks as zombies

### Solving the problem

We can enhance the documentation by translating this query https://github.com/astronomer/airflow/blob/main/airflow/jobs/scheduler_job_runner.py#L1721 to a layman readable text in our documentation.

### Anything else

It might also help to add developer contribution steps to reproduce zombies locally.

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Stats.incr("scheduler_heartbeat", 1, 1)
    def register_signals(self) -> None:
        """Register signals that stop child processes."""
        signal.signal(signal.SIGINT, self._exit_gracefully)
        signal.signal(signal.SIGTERM, self._exit_gracefully)
        signal.signal(signal.SIGUSR2, self._debug_dump)
    def _exit_gracefully(self, signum: int, frame: FrameType | None) -> None:
        """Clean up processor_agent to avoid leaving orphan processes."""
        if not _is_parent_process():
            
            return
        self.log.info("Exiting gracefully upon receiving signal %s", signum)
        if self.processor_agent:
            self.processor_agent.end()
        sys.exit(os.EX_OK)
    def _debug_dump(self, signum: int, frame: FrameType | None) -> None:
        if not _is_parent_process():
            
            return
        try:
            sig_name = signal.Signals(signum).name
        except Exception:
            sig_name = str(signum)
        self.log.info("%s\n%s received, printing debug\n%s", "-" * 80, sig_name, "-" * 80)
        self.job.executor.debug_dump()
        self.log.info("-" * 80)
    def __get_concurrency_maps(self, states: Iterable[TaskInstanceState], session: Session) -> ConcurrencyMap: