DOC: fixing GL08 errors for pandas.DatetimeIndex.as_unit and pandas.DatetimeIndex.freq
All GL08 Errors resolved in the following cases:

1. scripts/validate_docstrings.py --format=actions --errors=GL08 pandas.DatetimeIndex.as_unit
2. scripts/validate_docstrings.py --format=actions --errors=GL08 pandas.DatetimeIndex.freq

_Note: [6232a2e](https://github.com/pandas-dev/pandas/pull/57562/commits/6232a2ed2590fb8d8b43658adc009688cb30dce2) commit message was a typo, this commit is for GL08 errors_

- [x] xref https://github.com/pandas-dev/pandas/issues/57443
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

pre-commit.ci autofix

 pre-commit.ci autofix


 Thanks @jordan-d-murphy 