DOC: isin() docstring change DataFrame to pd.DataFrame
isin() docstring change DataFrame to pd.DataFrame
Hello @beepscore! Thanks for updating the PR.



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

##### Comment last updated on June 13, 2018 at 12:10 Hours UTC Simple enough. If you can correct the LINT issue then lgtm # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21403?src=pr&el=h1) Report
> Merging [#21403](https://codecov.io/gh/pandas-dev/pandas/pull/21403?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/415012f4f38ca0cf41717c51e49bd2349cba09a8?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/21403/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/21403?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #21403   +/-   ##
=======================================
  Coverage   91.89%   91.89%           
=======================================
  Files         153      153           
  Lines       49596    49596           
=======================================
  Hits        45576    45576           
  Misses       4020     4020
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.29% <ø> (ø)` | :arrow_up: |
| #single | `41.86% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/21403?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/21403/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.22% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21403?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/21403?src=pr&el=footer). Last update [415012f...ee2c818](https://codecov.io/gh/pandas-dev/pandas/pull/21403?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @beepscore Thanks! 
(I just changed `foo` to `df2`, many people are not familiar with 'foo', bar', ..)