ENH: .squeeze accepts axis parameter
 - [X] closes https://github.com/pandas-dev/pandas/issues/15339
 - [X] tests added / passed
 - [X] passes ``git diff upstream/master | flake8 --diff``
 - [X] whatsnew entry

@kernc Is there an issue for this? 
Can you give some rationale? Or show an example use case. Thanks. Now it is: https://github.com/pandas-dev/pandas/issues/15339. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15335?src=pr&el=h1) Report
> Merging [#15335](https://codecov.io/gh/pandas-dev/pandas/pull/15335?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/153da508a536a3ef203d9cd315c67b5fd3022a51?src=pr&el=desc) will **increase** coverage by `<.01%`.


```diff
@@            Coverage Diff             @@
##           master   #15335      +/-   ##
==========================================
+ Coverage   86.32%   86.32%   +<.01%     
==========================================
  Files         141      141              
  Lines       51165    51163       -2     
==========================================
- Hits        44169    44168       -1     
+ Misses       6996     6995       -1
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15335?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/compat/numpy/function.py](https://codecov.io/gh/pandas-dev/pandas/compare/153da508a536a3ef203d9cd315c67b5fd3022a51...44d3c54edfc5927c584aab63b5e059dc8e594cb4?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9mdW5jdGlvbi5weQ==) | `94.19% <ø> (-0.08%)` | :x: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/compare/153da508a536a3ef203d9cd315c67b5fd3022a51...44d3c54edfc5927c584aab63b5e059dc8e594cb4?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `96.33% <100%> (ø)` | :white_check_mark: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/compare/153da508a536a3ef203d9cd315c67b5fd3022a51...44d3c54edfc5927c584aab63b5e059dc8e594cb4?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `91.36% <ø> (+0.33%)` | :white_check_mark: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15335?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/15335?src=pr&el=footer). Last update [153da50...44d3c54](https://codecov.io/gh/pandas-dev/pandas/compare/153da508a536a3ef203d9cd315c67b5fd3022a51...44d3c54edfc5927c584aab63b5e059dc8e594cb4?el=footer&src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). thanks! Added a 2  comments on the documentation (see above and also the comment on the merged commit: https://github.com/pandas-dev/pandas/commit/87c2c2af6150d6e8fa8cfbc017fbfd52e7f8c5c7#commitcomment-20800784). 
@kernc would you like to do a follow-up PR?