Improve Airflow core docs regarding Dag versioning (AIP-63)

### Apache Airflow version 3.1.6 ### If "Other Airflow 3 version" selected, which one? _No response_ ### What happened? A task, when I need to clear a task in history, I find that there is no small square in this task, and the position of the small square is empty, so I can't jump to the task interface and can't clear it.  ### What you think should happen instead? For example, airflow2.x should be a white square under normal circumstances. ### How to reproduce Modify the task logic of dag, for example: change a->b to a->b->c ### Operating System Ubuntu 24.04 LTS ### Versions of Apache Airflow Providers _No response_ ### Deployment Other ### Deployment details _No response_ ### Anything else? _No response_ ### 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)