### 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._send_sla_callbacks_to_processor(dag)
        if callback:
            self.job.executor.send_callback(callback)
        else:
            self.log.debug("callback is empty")
    def _send_sla_callbacks_to_processor(self, dag: DAG) -> None:
        """Send SLA Callbacks to DagFileProcessor if tasks have SLAs set and check_slas=True."""
        if not settings.CHECK_SLAS:
            return
        if not any(isinstance(task.sla, timedelta) for task in dag.tasks):
            self.log.debug("Skipping SLA check for %s because no tasks in DAG have SLAs", dag)
            return
        if not dag.timetable.periodic:
            self.log.debug("Skipping SLA check for %s because DAG is not scheduled", dag)
            return
        dag_model = DagModel.get_dagmodel(dag.dag_id)
        if not dag_model:
            self.log.error("Couldn't find DAG %s in database!", dag.dag_id)
            return
        request = SlaCallbackRequest(
            full_filepath=dag.fileloc,
            dag_id=dag.dag_id,
            processor_subdir=dag_model.processor_subdir,
        )
        self.job.executor.send_callback(request)
    @provide_session
    def _fail_tasks_stuck_in_queued(self, session: Session = NEW_SESSION) -> None: