Doc: Adds example of categorical data for efficient storage and consistency across DataFrames
- [X] closes #12509 
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19245?src=pr&el=h1) Report
> Merging [#19245](https://codecov.io/gh/pandas-dev/pandas/pull/19245?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/7ed1f5371601f3300c8b4592c87159fb3eaec5cd?src=pr&el=desc) will **decrease** coverage by `0.24%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19245/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/19245?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19245      +/-   ##
==========================================
- Coverage   91.84%    91.6%   -0.25%     
==========================================
  Files         153      150       -3     
  Lines       49295    48864     -431     
==========================================
- Hits        45276    44761     -515     
- Misses       4019     4103      +84
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.97% <ø> (-0.27%)` | :arrow_down: |
| #single | `41.75% <ø> (-0.15%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19245?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/tseries/plotting.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvcGxvdHRpbmcucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/core/dtypes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2Jhc2UucHk=) | `47.61% <0%> (-44.28%)` | :arrow_down: |
| [pandas/plotting/\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb21wYXQucHk=) | `62% <0%> (-28.91%)` | :arrow_down: |
| [pandas/core/arrays/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2Jhc2UucHk=) | `60% <0%> (-24.15%)` | :arrow_down: |
| [pandas/io/s3.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3MzLnB5) | `72.72% <0%> (-13.64%)` | :arrow_down: |
| [pandas/core/missing.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvbWlzc2luZy5weQ==) | `85.9% <0%> (-5.75%)` | :arrow_down: |
| [pandas/io/formats/terminal.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvdGVybWluYWwucHk=) | `16.43% <0%> (-4.55%)` | :arrow_down: |
| [pandas/plotting/\_timeseries.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL190aW1lc2VyaWVzLnB5) | `60.82% <0%> (-4.49%)` | :arrow_down: |
| [pandas/core/reshape/tile.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS90aWxlLnB5) | `90.25% <0%> (-3.12%)` | :arrow_down: |
| [pandas/io/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2h0bWwucHk=) | `85.98% <0%> (-2.81%)` | :arrow_down: |
| ... and [67 more](https://codecov.io/gh/pandas-dev/pandas/pull/19245/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19245?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/19245?src=pr&el=footer). Last update [7ed1f53...d579ab6](https://codecov.io/gh/pandas-dev/pandas/pull/19245?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 closing as stale. if you'd like to continue pls ping.