DOC: fix punctuation in Timestamp/Timedelta docstrings
- [ ] xref #27977
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Add periods to Timestamp and Timedelta doctrings for the following attributes and methods:
```
pandas.Timestamp.resolution
pandas.Timestamp.tz
pandas.Timestamp.ceil
pandas.Timestamp.combine
pandas.Timestamp.floor
pandas.Timestamp.fromordinal
pandas.Timestamp.replace
pandas.Timestamp.round
pandas.Timestamp.weekday
pandas.Timedelta.ceil
pandas.Timedelta.floor
pandas.Timedelta.isoformat
pandas.Timedelta.round
```

I did not find the method for `pandas.Timestamp.isoweekday` this in the Timestamp source code. Was this deprecated ? @datapythonista 
Looks like this is failing `test_nat_doc_strings` in `pandas/tests/scalar/test_nat.py` - @sparalic can you take a look at that and update accordingly? @WillAyd I am not sure what's happening now. I fixed the errors associated is mismatching of overlapping methods per the CI logs . However, it still seems to be failing.  @sparalic the tests are failing because we have apparently tests that check that the docstring of `Timestamp.some_method` and `NaT.some_method` is the same (to ensure they keep being consistent). 
So you will need to make the same changes (adding the periods) for `NaT` as well. You can find those in `pandas/_libs/tslibs/nattype.pyx` @sparalic see my last comment about how to get this PR passing CI, if you have some time to update it, that would be welcome! @jorisvandenbossche I am sorry for the delay. I found the culprits and updated them all. I think it should be all set now.