DOC: fixed docstring of timedelta.ceil to match docstring of datetimeindex…
This PR fixes the document for pandas Timedelta.ceil.

It also adds summary to pandas Timedelta.ceil, Timedelta.floor and Timedelta.round to pass the [docstring validation](https://pandas.pydata.org/docs/dev/development/contributing_documentation.html#updating-a-pandas-docstring)

- [x] closes #59902 (Replace xxxx with the GitHub issue number)
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).


Attaching screenshots for changes, tested in local:
<img width="1421" alt="Screenshot 2024-10-16 at 14 02 45" src="https://github.com/user-attachments/assets/e4ae20a7-4ee7-462f-b47a-2fcb6416f450">
<img width="1409" alt="Screenshot 2024-10-16 at 12 48 42" src="https://github.com/user-attachments/assets/68af401d-6b6b-4f12-bd7a-fdb0d129aeec">
<img width="1403" alt="Screenshot 2024-10-16 at 12 48 52" src="https://github.com/user-attachments/assets/c8219cb0-a7ea-47f1-9d1f-acc8f76d1b57">

Thanks for the PR but appears https://github.com/pandas-dev/pandas/pull/60047 was opened first so let's allow that contributor to address this issue first. Closing but happy to have your help on other issues