DOC: Validate parameter types in docstrings (e.g. str instead of string)
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

Related to #20298. Fixes the bullet "Using string, boolean, integer in the param descriptions (should be str, bool, int)".
Hello @Moisan! Thanks for updating the PR.

 - There are no PEP8 issues in the file [`scripts/tests/test_validate_docstrings.py`](https://github.com/Moisan/pandas/blob/87638fe46df61756f50530b95c0cbac49618568a/scripts/tests/test_validate_docstrings.py) !

 - There are no PEP8 issues in the file [`scripts/validate_docstrings.py`](https://github.com/Moisan/pandas/blob/87638fe46df61756f50530b95c0cbac49618568a/scripts/validate_docstrings.py) !



##### Comment last updated on October 15, 2018 at 14:38 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=h1) Report
> Merging [#23165](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/cf11f71e423be65e9c2ae83ea1bab8b69ee79ca4?src=pr&el=desc) will **increase** coverage by `0.04%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23165/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23165      +/-   ##
==========================================
+ Coverage   92.14%   92.19%   +0.04%     
==========================================
  Files         170      169       -1     
  Lines       51017    50959      -58     
==========================================
- Hits        47011    46980      -31     
+ Misses       4006     3979      -27
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.61% <ø> (+0.04%)` | :arrow_up: |
| #single | `42.29% <ø> (-0.02%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb21wYXQucHk=) | `87.5% <0%> (-3.81%)` | :arrow_down: |
| [pandas/compat/numpy/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9fX2luaXRfXy5weQ==) | `92.85% <0%> (-1.09%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.82% <0%> (-0.07%)` | :arrow_down: |
| [pandas/core/util/hashing.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdXRpbC9oYXNoaW5nLnB5) | `98.4% <0%> (ø)` | :arrow_up: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.11% <0%> (ø)` | :arrow_up: |
| [pandas/compat/pickle\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9waWNrbGVfY29tcGF0LnB5) | `75.6% <0%> (ø)` | :arrow_up: |
| [pandas/core/dtypes/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2NvbW1vbi5weQ==) | `95.11% <0%> (ø)` | :arrow_up: |
| [pandas/core/arrays/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL19faW5pdF9fLnB5) | `100% <0%> (ø)` | :arrow_up: |
| [pandas/core/sparse/api.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FwaS5weQ==) | `100% <0%> (ø)` | :arrow_up: |
| [pandas/core/sparse/array.py](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FycmF5LnB5) | | |
| ... and [8 more](https://codecov.io/gh/pandas-dev/pandas/pull/23165/diff?src=pr&el=tree-more) | |

------

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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=footer). Last update [cf11f71...26bf7be](https://codecov.io/gh/pandas-dev/pandas/pull/23165?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks @Moisan !