Add example to `Dataframe.head()` method's docstring.
closes #18691
closes #16416

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=h1) Report
> Merging [#18746](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/96439fb13e941100080a8fb5c78b7b291a2dd2fe?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18746/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18746      +/-   ##
==========================================
- Coverage   91.59%   91.57%   -0.02%     
==========================================
  Files         153      153              
  Lines       51364    51364              
==========================================
- Hits        47046    47037       -9     
- Misses       4318     4327       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.44% <ø> (ø)` | :arrow_up: |
| #single | `40.74% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `95.9% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18746?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/18746?src=pr&el=footer). Last update [96439fb...439f6be](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=h1) Report
> Merging [#18746](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/96439fb13e941100080a8fb5c78b7b291a2dd2fe?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18746/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18746      +/-   ##
==========================================
+ Coverage   91.59%   91.59%   +<.01%     
==========================================
  Files         153      153              
  Lines       51364    51364              
==========================================
+ Hits        47046    47049       +3     
+ Misses       4318     4315       -3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.46% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.74% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `95.9% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18746/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `66.52% <0%> (+1.73%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18746?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/18746?src=pr&el=footer). Last update [96439fb...0ac5fab](https://codecov.io/gh/pandas-dev/pandas/pull/18746?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 so you are before #18746 so if you want to add an example for .tail and a See Also section (closes #18691) would be great.
 superseded by #18749 

thanks @dpshelio love to have your contribution on another issue!