DOC: correct min_count param docstring
correct min_count param docstring for function  ’Series.prod‘， ’Series.sum',  'DataFrame.prod', 'DataFrame.sum'

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19836?src=pr&el=h1) Report
> Merging [#19836](https://codecov.io/gh/pandas-dev/pandas/pull/19836?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b585e3b5145a73cc7480db9a3b0c3ce7bd55511e?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/19836/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/19836?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19836      +/-   ##
==========================================
+ Coverage   91.57%    91.6%   +0.02%     
==========================================
  Files         150      150              
  Lines       48903    48908       +5     
==========================================
+ Hits        44785    44804      +19     
+ Misses       4118     4104      -14
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.98% <ø> (+0.02%)` | :arrow_up: |
| #single | `41.77% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19836?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/19836/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `95.93% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/19836/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `83.64% <0%> (-0.21%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/19836/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.23% <0%> (ø)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/19836/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `66.95% <0%> (+1.73%)` | :arrow_up: |
| [pandas/core/reshape/tile.py](https://codecov.io/gh/pandas-dev/pandas/pull/19836/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS90aWxlLnB5) | `92.94% <0%> (+2.68%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19836?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/19836?src=pr&el=footer). Last update [b585e3b...22fd6bb](https://codecov.io/gh/pandas-dev/pandas/pull/19836?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Hello @ZhuBaohe! Thanks for updating the PR.



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

##### Comment last updated on February 22, 2018 at 23:16 Hours UTC thanks!