DOC: Added 'Modules Privacy Has Changed' section to overview.rst
- [x] closes #22942 
- [x] tests passed

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23038?src=pr&el=h1) Report
> Merging [#23038](https://codecov.io/gh/pandas-dev/pandas/pull/23038?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/ce1f81f8bcf038072e0ecb661310984076c4e7de?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/23038/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23038?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23038      +/-   ##
==========================================
+ Coverage   92.19%   92.22%   +0.02%     
==========================================
  Files         169      169              
  Lines       50873    51261     +388     
==========================================
+ Hits        46904    47277     +373     
- Misses       3969     3984      +15
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.66% <ø> (+0.04%)` | :arrow_up: |
| #single | `42.23% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23038?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/feather\_format.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2ZlYXRoZXJfZm9ybWF0LnB5) | `77.14% <0%> (-8.58%)` | :arrow_down: |
| [pandas/plotting/\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb21wYXQucHk=) | `87.5% <0%> (-3.81%)` | :arrow_down: |
| [pandas/core/ops.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvb3BzLnB5) | `94.24% <0%> (-2.95%)` | :arrow_down: |
| [pandas/core/dtypes/concat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2NvbmNhdC5weQ==) | `96.34% <0%> (-2.84%)` | :arrow_down: |
| [pandas/core/arrays/datetimelike.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lbGlrZS5weQ==) | `93.21% <0%> (-2.35%)` | :arrow_down: |
| [pandas/core/internals/concat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzL2NvbmNhdC5weQ==) | `96.83% <0%> (-1.54%)` | :arrow_down: |
| [pandas/core/indexes/period.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9wZXJpb2QucHk=) | `92.27% <0%> (-1.39%)` | :arrow_down: |
| [pandas/compat/numpy/function.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9mdW5jdGlvbi5weQ==) | `87.13% <0%> (-1.36%)` | :arrow_down: |
| [pandas/compat/numpy/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9fX2luaXRfXy5weQ==) | `92.85% <0%> (-1.09%)` | :arrow_down: |
| [pandas/core/internals/managers.py](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzL21hbmFnZXJzLnB5) | `95.73% <0%> (-0.94%)` | :arrow_down: |
| ... and [75 more](https://codecov.io/gh/pandas-dev/pandas/pull/23038/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23038?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/23038?src=pr&el=footer). Last update [ce1f81f...b9cae7e](https://codecov.io/gh/pandas-dev/pandas/pull/23038?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Let me know if this is correct. The neighboring sections are a bit strange, but "Package Overview" seems
like the right place.

Maybe we could expand the new section a bit with text describing the
modules that are public?

On Fri, Oct 26, 2018 at 3:38 AM Joris Van den Bossche <
notifications@github.com> wrote:

> *@jorisvandenbossche* commented on this pull request.
>
> I think the text around it suggested by Tom in #23038 (comment)
> <https://github.com/pandas-dev/pandas/pull/23038#discussion_r223694209>
> would still be good to add
>
> Do we have a better place for this than overview.rst ? It now feels a bit
> out of place between "Institutional partners" and "License"
>
> —
> You are receiving this because you commented.
> Reply to this email directly, view it on GitHub
> <https://github.com/pandas-dev/pandas/pull/23038#pullrequestreview-168722317>,
> or mute the thread
> <https://github.com/notifications/unsubscribe-auth/ABQHIlw25ytIpc1-gQGdbfbdnNYChqjxks5uosoPgaJpZM4XMZ1w>
> .
>
 Adding public modules to this would be a good idea.

 I'm unsure about this. I see the value in documenting what is private or public, but:
- I agree that between partners and license doesn't seem to be the right place
- `api.rst` is already the list of what is public, and it's huge, we probably don't want to repeat this here, and I find quite confusing to have a public modules list with a subset

@TomAugspurger  What about moving this as a short `.. note::` section at the beginning of `api.rst` to warn about what is private instead? I notice now that we *do* have a note like that at the top of api.rst:
http://pandas-docs.github.io/pandas-docs-travis/api.html

On Tue, Nov 20, 2018 at 8:58 AM Marc Garcia <notifications@github.com>
wrote:

> I'm unsure about this. I see the value in documenting what is private or
> public, but:
>
>    - I agree that between partners and license doesn't seem to be the
>    right place
>    - api.rst is already the list of what is public, and it's huge, we
>    probably don't want to repeat this here, and I find quite confusing to have
>    a public modules list with a subset
>
> @TomAugspurger <https://github.com/TomAugspurger> What about moving this
> as a short .. note:: section at the beginning of api.rst to warn about
> what is private instead?
>
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub
> <https://github.com/pandas-dev/pandas/pull/23038#issuecomment-440302465>,
> or mute the thread
> <https://github.com/notifications/unsubscribe-auth/ABQHIg-zcKqMpJr8j0Yin3KNY1DZTKeAks5uxBiigaJpZM4XMZ1w>
> .
>
 That's funny, didn't see that. Closing this then, feel free to reopen if you think something else is needed. Sorry for missing that @aparimeet. Let me know if you want help starting on
a new issue.

On Tue, Nov 20, 2018 at 9:06 AM Marc Garcia <notifications@github.com>
wrote:

> Closed #23038 <https://github.com/pandas-dev/pandas/pull/23038>.
>
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub
> <https://github.com/pandas-dev/pandas/pull/23038#event-1977594802>, or mute
> the thread
> <https://github.com/notifications/unsubscribe-auth/ABQHIv8yHVuV8NbAV_ySP5gae0CLsLfMks5uxBp6gaJpZM4XMZ1w>
> .
>
