DOC: Fixing flake8 errors in cookbook.rst
- [x] closes #23794
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

The CI failed because of `doc/source/cookbook.rst:1324:9: E303 too many blank lines (3)`.

If you can, would be nice to run locally after the fixes:
- `LINT=1 ./ci/code_checks.sh`
- `flake8-rst doc/source/cookbook.rst`

To see that everything is correct, so we can merge. > The CI failed because of `doc/source/cookbook.rst:1324:9: E303 too many blank lines (3)`.
> 
> If you can, would be nice to run locally after the fixes:
> 
>     * `LINT=1 ./ci/code_checks.sh`
> 
>     * `flake8-rst doc/source/cookbook.rst`
> 
> 
> To see that everything is correct, so we can merge.

Noted your suggestions @datapythonista . I have submitted another PR as this build failed the tests. I will make all these changes and resubmit. I am closing the PR till these are resolved.  You don't need to open new PR for every change.

Just make the changes in the branch you used for the PR, commit and push. The PR will be updated, and it make things much easier for us (and for you I think) this way. The tests pass on my local. Not sure why automate test is failing.  # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23837?src=pr&el=h1) Report
> Merging [#23837](https://codecov.io/gh/pandas-dev/pandas/pull/23837?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/4f16dff3d9cdcd9c4465a02df773885f8862035e?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23837/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23837?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #23837      +/-   ##
==========================================
+ Coverage   92.29%   92.29%   +<.01%     
==========================================
  Files         161      161              
  Lines       51497    51498       +1     
==========================================
+ Hits        47528    47530       +2     
+ Misses       3969     3968       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.69% <ø> (ø)` | :arrow_up: |
| #single | `42.43% <ø> (+0.1%)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23837?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/parsers.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhcnNlcnMucHk=) | `95.29% <0%> (-0.28%)` | :arrow_down: |
| [pandas/io/pytables.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3B5dGFibGVzLnB5) | `92.3% <0%> (-0.05%)` | :arrow_down: |
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `97.6% <0%> (-0.01%)` | :arrow_down: |
| [pandas/core/indexes/multi.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9tdWx0aS5weQ==) | `95.49% <0%> (-0.01%)` | :arrow_down: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `96.84% <0%> (-0.01%)` | :arrow_down: |
| [pandas/core/reshape/pivot.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS9waXZvdC5weQ==) | `96.55% <0%> (ø)` | :arrow_up: |
| [pandas/io/json/normalize.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vbm9ybWFsaXplLnB5) | `96.87% <0%> (ø)` | :arrow_up: |
| [pandas/io/packers.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhY2tlcnMucHk=) | `88.08% <0%> (ø)` | :arrow_up: |
| [pandas/core/util/hashing.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdXRpbC9oYXNoaW5nLnB5) | `98.4% <0%> (ø)` | :arrow_up: |
| [pandas/core/strings.py](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3RyaW5ncy5weQ==) | `98.58% <0%> (ø)` | :arrow_up: |
| ... and [40 more](https://codecov.io/gh/pandas-dev/pandas/pull/23837/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23837?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/23837?src=pr&el=footer). Last update [4f16dff...d57be90](https://codecov.io/gh/pandas-dev/pandas/pull/23837?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks @saurav2608 !