DOC: Improve pandas.Series.plot.kde docstring and kwargs rewording for whole file
 Initial docstring assigned to the Barcelona Chapter for the documentation sprint.

Credits to @arnau126 who also contributed to this change.

Also, rewording of `kwargs` argument explanation for the whole file, where we refer to the `pandas.Series.plot` docstring for info.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=h1) Report
> Merging [#20041](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b6691127523f965003dbf877a358c81af5012989?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/20041/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #20041      +/-   ##
==========================================
- Coverage   91.69%   91.69%   -0.01%     
==========================================
  Files         150      150              
  Lines       49112    49112              
==========================================
- Hits        45035    45033       -2     
- Misses       4077     4079       +2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.07% <ø> (-0.01%)` | :arrow_down: |
| #single | `41.86% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/20041/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `82.23% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/20041/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `83.64% <0%> (-0.21%)` | :arrow_down: |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=footer). Last update [b669112...5099d08](https://codecov.io/gh/pandas-dev/pandas/pull/20041?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jorisvandenbossche Thanks for the review! I've updated the PR in response to your comments. There is also issue https://github.com/pandas-dev/pandas/issues/11042 on adding the explanation of more keyword arguments.  What about the travis failures? Is it just that the tests are flaky, or the docstring changes can really break something? I.e. are docstring doctests executed by CI? > What about the travis failures? Is it just that the tests are flaky, or the docstring changes can really break something? I.e. are docstring doctests executed by CI?

Don't worry about those, we have some failing tests due to the new matplotlib release we need to fix. I believe this should be ready to go. @jorisvandenbossche please do a last review! @dukebody Thanks! We will do the follow-up in https://github.com/pandas-dev/pandas/pull/20236