docs: fix SS06, PR08, RT02, RT03, SA04 in pandas.DatetimeIndex.indexe…
…r_at_time

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

 Fix : https://github.com/pandanistas/pandanistas_sprint_ui2020/issues/8

Hello @rahmadiantio! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/core/indexes/datetimes.py`](https://github.com/pandas-dev/pandas/blob/739b94e30af46c3b34c517a99e4da37eb5ec4fe3/pandas/core/indexes/datetimes.py):

> [Line 718:72](https://github.com/pandas-dev/pandas/blob/739b94e30af46c3b34c517a99e4da37eb5ec4fe3/pandas/core/indexes/datetimes.py#L718): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace
> [Line 723:72](https://github.com/pandas-dev/pandas/blob/739b94e30af46c3b34c517a99e4da37eb5ec4fe3/pandas/core/indexes/datetimes.py#L723): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace



##### Comment last updated at 2020-02-29 05:20:26 UTC Closing as stale. @rahmadiantio let us know if you finally want to address the review comments.