DOC: GH39672 Pandas dataframe pct_change function arguments
- [x] closes #39672
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

Running `validate_docstrings.py` produces:
```
# python scripts/validate_docstrings.py pandas.DataFrame.pct_change

################################################################################
################### Docstring (pandas.DataFrame.pct_change)  ###################
################################################################################
...
>>> df = pd.DataFrame({
...     '2016': [1769950, 30586265],
...     '2015': [1500923, 40912316],
...     '2014': [1371819, 41403351]},
...     index=['GOOG', 'APPL'])
>>> df
          2016      2015      2014
GOOG   1769950   1500923   1371819
APPL  30586265  40912316  41403351

>>> df.pct_change(axis='columns', periods=-1)
          2016      2015  2014
GOOG  0.179241  0.094112   NaN
APPL -0.252395 -0.011860   NaN

################################################################################
################################## Validation ##################################
################################################################################

1 Errors found:
	The first line of the Returns section should contain only the type, unless multiple values are being returned
```

Where the last cell with `>>> df.pct_change(axis='columns', periods=-1)` is the docstring I've updated, prior to making this edit the same "1 Error found" message was generated. Running `# ./ci/code_checks.sh ` yields one failure but this is unrelated (surely?) to my PR so I'm not sure what to do about it?

```
Doctests computation DONE
Doctests dtypes
..........................................F...................                                                                                                                                                                         [100%]
================================================================================================================== FAILURES ==================================================================================================================
____________________________________________________________________________________________ [doctest] pandas.core.dtypes.dtypes.DatetimeTZDtype _____________________________________________________________________________________________
654     ------
655     pytz.UnknownTimeZoneError
656         When the requested timezone cannot be found.
657 
658     Examples
659     --------
660     >>> pd.DatetimeTZDtype(tz='UTC')
661     datetime64[ns, UTC]
662 
663     >>> pd.DatetimeTZDtype(tz='dateutil/US/Central')
Expected:
    datetime64[ns, tzfile('/usr/share/zoneinfo/US/Central')]
Got:
    datetime64[ns, tzfile('US/Central')]

/home/pandas-ianozsvald/pandas/core/dtypes/dtypes.py:663: DocTestFailure

``` @MarcoGorelli (following up on Gitter but I don't know if you've signed out of there for now) - do I need to do anything or does the perhaps get re-run automatically? I'm not sure what my next step might be? Cheers, Ian. Thanks @ianozsvald - the `dtypes` doctest check works fine for me running it on your branch, not sure why you were seeing an error. CI failures are unrelated