DOC: Fix flake8 issues in doc/source/whatsnew/v0.17.*.rst
- [x] closes #24235
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hi! @datapythonista 
I have a few queries regarding some changes - currently the output of 
`flake8-rst doc/source/whatsnew/v0.17.*` is:

doc/source/whatsnew/v0.17.0.rst:177:22: E225 missing whitespace around operator
doc/source/whatsnew/v0.17.0.rst:177:22: E999 SyntaxError: invalid syntax
doc/source/whatsnew/v0.17.0.rst:177:26: E225 missing whitespace around operator
doc/source/whatsnew/v0.17.0.rst:750:14: E711 comparison to None should be 'if cond is None:'
doc/source/whatsnew/v0.17.0.rst:757:6: E711 comparison to None should be 'if cond is None:'
doc/source/whatsnew/v0.17.0.rst:772:12: E711 comparison to None should be 'if cond is None:'
doc/source/whatsnew/v0.17.1.rst:87:11: F821 undefined name 'DataFrame'

The errors on line 177 are due to `df.plot.<TAB>` - which is a valid operation in pandas but is giving an error here.

The next 3 errors are due to a comparison of a series vs None: `s == None`,
but an error is thrown requesting an `if` loop be added, along with its indentation block.

What would be the best way to resolve these?
 we fixed them before with a `noqa` comment. If you do a `grep "<TAB>" doc/*`, `grep "== None"`... you should find examples. also, please merge master and fix the conflicts when you update the PR @aqurilla do you have time to finish this PR? Hi @datapythonista yes, I was travelling and should be able to finish this by tomorrow @aqurilla do you have time to finish this? # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=h1) Report
> Merging [#24340](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d5283eadaf51af855d6aee0692dfa2ae91feb633?src=pr&el=desc) will **increase** coverage by `60.39%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24340/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=tree)

```diff
@@             Coverage Diff             @@
##           master   #24340       +/-   ##
===========================================
+ Coverage   31.88%   92.28%   +60.39%     
===========================================
  Files         166      162        -4     
  Lines       52413    51835      -578     
===========================================
+ Hits        16714    47834    +31120     
+ Misses      35699     4001    -31698
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.68% <ø> (+60.39%)` | :arrow_up: |
| #single | `43% <ø> (+11.11%)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/computation/check.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tcHV0YXRpb24vY2hlY2sucHk=) | `90.9% <0%> (-1.4%)` | :arrow_down: |
| [pandas/core/dtypes/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2dlbmVyaWMucHk=) | `100% <0%> (ø)` | :arrow_up: |
| [pandas/core/arrays/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL19faW5pdF9fLnB5) | `100% <0%> (ø)` | :arrow_up: |
| [pandas/core/arrays/numpy\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL251bXB5Xy5weQ==) | | |
| [pandas/core/arrays/array\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2FycmF5Xy5weQ==) | | |
| [pandas/core/arrays/\_ranges.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL19yYW5nZXMucHk=) | | |
| [pandas/core/internals/arrays.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzL2FycmF5cy5weQ==) | | |
| [pandas/util/\_test\_decorators.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX3Rlc3RfZGVjb3JhdG9ycy5weQ==) | `90.54% <0%> (+4.05%)` | :arrow_up: |
| [pandas/core/config\_init.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29uZmlnX2luaXQucHk=) | `99.24% <0%> (+9.84%)` | :arrow_up: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `58.3% <0%> (+10.03%)` | :arrow_up: |
| ... and [128 more](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24340?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/24340?src=pr&el=footer). Last update [d5283ea...245d21e](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=h1) Report
> Merging [#24340](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d5283eadaf51af855d6aee0692dfa2ae91feb633?src=pr&el=desc) will **increase** coverage by `60.43%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24340/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=tree)

```diff
@@             Coverage Diff             @@
##           master   #24340       +/-   ##
===========================================
+ Coverage   31.88%   92.32%   +60.43%     
===========================================
  Files         166      166               
  Lines       52413    52440       +27     
===========================================
+ Hits        16714    48416    +31702     
+ Misses      35699     4024    -31675
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.75% <ø> (+60.45%)` | :arrow_up: |
| #single | `43.01% <ø> (+11.12%)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/\_test\_decorators.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX3Rlc3RfZGVjb3JhdG9ycy5weQ==) | `90.54% <0%> (+4.05%)` | :arrow_up: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `57.91% <0%> (+9.65%)` | :arrow_up: |
| [pandas/core/config\_init.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29uZmlnX2luaXQucHk=) | `99.24% <0%> (+9.84%)` | :arrow_up: |
| [pandas/core/reshape/util.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS91dGlsLnB5) | `100% <0%> (+11.53%)` | :arrow_up: |
| [pandas/core/api.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXBpLnB5) | `100% <0%> (+13.33%)` | :arrow_up: |
| [pandas/compat/numpy/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9udW1weS9fX2luaXRfXy5weQ==) | `92.85% <0%> (+14.28%)` | :arrow_up: |
| [pandas/io/formats/console.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvY29uc29sZS5weQ==) | `74.24% <0%> (+16.66%)` | :arrow_up: |
| [pandas/core/dtypes/inference.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2luZmVyZW5jZS5weQ==) | `98.46% <0%> (+18.46%)` | :arrow_up: |
| [pandas/plotting/\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb21wYXQucHk=) | `87.5% <0%> (+18.75%)` | :arrow_up: |
| [pandas/core/indexes/api.py](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9hcGkucHk=) | `99% <0%> (+20.79%)` | :arrow_up: |
| ... and [125 more](https://codecov.io/gh/pandas-dev/pandas/pull/24340/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24340?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/24340?src=pr&el=footer). Last update [d5283ea...29c9163](https://codecov.io/gh/pandas-dev/pandas/pull/24340?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Hi @datapythonista , please have a look,
sorry for the delay! ping on green. @jreback, please have a look thanks @aqurilla 