DOC: add example on json_normalize
 - [v ] closes #16415
 - [v ] tests added / passed
 - [v ] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff``
 - [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=h1) Report
> Merging [#16438](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/49ec31bbaeca81a6f58fc1be26fe80f3ac188cdd?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16438/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16438      +/-   ##
==========================================
- Coverage   90.42%   90.42%   -0.01%     
==========================================
  Files         161      161              
  Lines       51023    51023              
==========================================
- Hits        46138    46137       -1     
- Misses       4885     4886       +1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.26% <ø> (-0.01%)` | :arrow_down: |
| #single | `40.17% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/json/normalize.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vbm9ybWFsaXplLnB5) | `96.93% <ø> (ø)` | :arrow_up: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `91.05% <0%> (-0.34%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16438?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/16438?src=pr&el=footer). Last update [49ec31b...c85a318](https://codecov.io/gh/pandas-dev/pandas/pull/16438?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/16438?src=pr&el=h1) Report
> Merging [#16438](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/24b6349c013fb9e59ea7fa4b1d40088026c32d25?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/16438/graphs/tree.svg?token=eZ4WkYLtcO&height=150&src=pr&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16438      +/-   ##
==========================================
+ Coverage      91%   91.01%   +<.01%     
==========================================
  Files         162      162              
  Lines       49547    49547              
==========================================
+ Hits        45091    45095       +4     
+ Misses       4456     4452       -4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.79% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.25% <ø> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/json/normalize.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vbm9ybWFsaXplLnB5) | `96.93% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.72% <0%> (-0.1%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.33% <0%> (+0.09%)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.05% <0%> (+1.81%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16438?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/16438?src=pr&el=footer). Last update [24b6349...88fe776](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 can you rebase and update according to comments. Resolved the small comments. @zzgao Thanks for the example! # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=h1) Report
> Merging [#16438](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/24b6349c013fb9e59ea7fa4b1d40088026c32d25?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/16438/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16438      +/-   ##
==========================================
+ Coverage      91%   91.01%   +<.01%     
==========================================
  Files         162      162              
  Lines       49547    49547              
==========================================
+ Hits        45091    45095       +4     
+ Misses       4456     4452       -4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.79% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.25% <ø> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/json/normalize.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2lvL2pzb24vbm9ybWFsaXplLnB5) | `96.93% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.72% <0%> (-0.1%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.33% <0%> (+0.09%)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.05% <0%> (+1.81%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16438?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/16438?src=pr&el=footer). Last update [24b6349...88fe776](https://codecov.io/gh/pandas-dev/pandas/pull/16438?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
