Correct assert_frame_equal doc string
Correct default values in assert_frame_equal doc string

@WillAyd 
```################################################################################
################################## Validation ##################################
################################################################################

Warnings found:
        No extended summary found
        See Also section not found
        No examples section found
Docstring for "pandas.util.testing.assert_frame_equal" correct. :)
``` # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22552?src=pr&el=h1) Report
> Merging [#22552](https://codecov.io/gh/pandas-dev/pandas/pull/22552?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/98fb53ca2d64658749e9f182b391002ef3500c1b?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/22552/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22552?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22552   +/-   ##
=======================================
  Coverage   92.04%   92.04%           
=======================================
  Files         169      169           
  Lines       50787    50787           
=======================================
  Hits        46745    46745           
  Misses       4042     4042
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.45% <ø> (ø)` | :arrow_up: |
| #single | `42.29% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/22552?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/22552/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `85.75% <ø> (ø)` | :arrow_up: |
| [pandas/core/strings.py](https://codecov.io/gh/pandas-dev/pandas/pull/22552/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3RyaW5ncy5weQ==) | `98.63% <0%> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22552?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/22552?src=pr&el=footer). Last update [98fb53c...6a861d7](https://codecov.io/gh/pandas-dev/pandas/pull/22552?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Hello @pablojim! Thanks for updating the PR.



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

##### Comment last updated on September 03, 2018 at 11:52 Hours UTC