DOC: update the pandas.DataFrame.clip_lower docstring
Checklist for the pandas documentation sprint (ignore this if you are doing
an unrelated PR):

- [X] PR title is "DOC: update the <your-function-or-method> docstring"
- [X] The validation script passes: `scripts/validate_docstrings.py <your-function-or-method>`
- [X] The PEP8 style check passes: `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] The html version looks good: `python doc/make.py --single <your-function-or-method>`
- [X] It has been proofread on language by another sprint participant

Please include the output of the validation script below between the "```" ticks:

```
################################################################################
################################## Validation ##################################
################################################################################

Docstring for "pandas.DataFrame.clip_lower" correct. :)
```

If the validation script still gives errors, but you think there is a good reason
to deviate in this case (and there are certainly such cases), please state this
explicitly.


This PR is for `clip` which is quite similar: #20212. Your changes look great, but I'd take a look at the discussion there to see if you see anything you can improve.

The `Return` section is probably worth changing to the format in the first example here:
https://python-sprints.github.io/pandas/guide/pandas_docstring.html#section-4-returns-or-yields # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@1986dbe`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/20289/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #20289   +/-   ##
=========================================
  Coverage          ?   91.73%           
=========================================
  Files             ?      150           
  Lines             ?    49148           
  Branches          ?        0           
=========================================
  Hits              ?    45087           
  Misses            ?     4061           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.12% <100%> (?)` | |
| #single | `41.9% <71.42%> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/20289/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `95.85% <100%> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=footer). Last update [1986dbe...e48d49b](https://codecov.io/gh/pandas-dev/pandas/pull/20289?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Rebased (another PR also already updated this docstring, so the diff became somewhat smaller).

Thanks @adatasetaday !