DOC: improve docstring of function where
Clarified parameters `cond` and `other`.
Added example with scalar `other`.
Hello @JennaVergeynst! Thanks for updating the PR.



Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on September 25, 2017 at 12:54 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=h1) Report
> Merging [#17665](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/83c9205971bd173692286187024ae30aae9ffc39?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17665/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17665      +/-   ##
==========================================
- Coverage   91.23%   91.21%   -0.02%     
==========================================
  Files         163      163              
  Lines       49808    49808              
==========================================
- Hits        45442    45433       -9     
- Misses       4366     4375       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.01% <100%> (ø)` | :arrow_up: |
| #single | `40.32% <100%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `92.07% <100%> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.73% <0%> (-0.1%)` | :arrow_down: |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=footer). Last update [83c9205...cf8f081](https://codecov.io/gh/pandas-dev/pandas/pull/17665?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @JennaVergeynst 