DOC: improve read_excel docstring
closes #16582
closes #16580
closes #16655


# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=h1) Report
> Merging [#16658](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/dc716b061d9a0bc6a59f4e02d72b9952cce28927?src=pr&el=desc) will **increase** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16658/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16658      +/-   ##
==========================================
+ Coverage   90.93%   90.96%   +0.02%     
==========================================
  Files         161      161              
  Lines       49266    49266              
==========================================
+ Hits        44801    44813      +12     
+ Misses       4465     4453      -12
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.72% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.22% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/excel.py](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsLnB5) | `80.55% <ø> (ø)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.05% <0%> (+1.81%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16658?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/16658?src=pr&el=footer). Last update [dc716b0...b696a92](https://codecov.io/gh/pandas-dev/pandas/pull/16658?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 lgtm. thanks @chris-b1 