DOC: added plotting module to the api reference docs
- [x ] closes #19777
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

@jreback Thanks for the quick feedback. The only changes I made were to doc/source/api.rst. Those files were automatically generated by the docs. Should I not include them in the commit? They look like they might be part of the examples. no your don’t need to include them  # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=h1) Report
> Merging [#19780](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/af5e8ecc800493c0f2578daa25354ae32e08b544?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19780/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #19780   +/-   ##
=======================================
  Coverage   91.61%   91.61%           
=======================================
  Files         150      150           
  Lines       48887    48887           
=======================================
  Hits        44786    44786           
  Misses       4101     4101
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.98% <ø> (ø)` | :arrow_up: |
| #single | `41.8% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19780?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/19780?src=pr&el=footer). Last update [af5e8ec...5ded993](https://codecov.io/gh/pandas-dev/pandas/pull/19780?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/19780?src=pr&el=h1) Report
> Merging [#19780](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/af5e8ecc800493c0f2578daa25354ae32e08b544?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19780/graphs/tree.svg?height=150&src=pr&token=eZ4WkYLtcO&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #19780   +/-   ##
=======================================
  Coverage   91.61%   91.61%           
=======================================
  Files         150      150           
  Lines       48887    48887           
=======================================
  Hits        44786    44786           
  Misses       4101     4101
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.98% <ø> (ø)` | :arrow_up: |
| #single | `41.8% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19780?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/19780?src=pr&el=footer). Last update [af5e8ec...e71a854](https://codecov.io/gh/pandas-dev/pandas/pull/19780?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Can you also remove the `/doc/test.json` file? (check the diff) Ok I've made some changes

- removed the images
- merged the two plotting module sections

So this is all ready to go.

One thought though. I don't find it intuitive that the plotting module is nested under the style section. As a relatively new user this is confusing to me. Perhaps the plotting module warrants its own section? instead of:

```
Plotting
~~~~~~~~
```
Perhaps:
```
Plotting
--------
``` Ah yes, I'll remove that as well.

UPDATE: done Regarding the header level, you are certainly right (I suppose that's an oversight). You can make that change. Ok thanks for the feedback Joris. This looks good to me but let me know if there's anything else I should do. I'm new to contributing to Pandas so if I'm leaving out any best practices or conventions I'd like to correct that. @jreback I've removed all the extra files from this branch. Any other changes I need to make? thanks @mehemken 