### 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)

self,
        guard: CommitProhibitorGuard,
        dag_runs: Iterable[DagRun],
        session: Session,
    ) -> list[tuple[DagRun, DagCallbackRequest | None]]:
        """Make scheduling decisions for all `dag_runs`."""
        callback_tuples = [(run, self._schedule_dag_run(run, session=session)) for run in dag_runs]
        guard.commit()
        return callback_tuples
    def _schedule_dag_run(
        self,
        dag_run: DagRun,
        session: Session,
    ) -> DagCallbackRequest | None:
        """
        Make scheduling decisions about an individual dag run.
        :param dag_run: The DagRun to schedule
        :return: Callback that needs to be executed
        """
        callback: DagCallbackRequest | None = None
        dag = dag_run.dag = self.dagbag.get_dag(dag_run.dag_id, session=session)
        
        query = (
            select(DagModel).where(DagModel.dag_id == dag_run.dag_id).options(joinedload(DagModel.parent_dag))
        )