Improve documentation for assert_frame|series_equal #26101
- [x] closes #26101 
- [ ] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26106?src=pr&el=h1) Report
> Merging [#26106](https://codecov.io/gh/pandas-dev/pandas/pull/26106?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/aad77394b14f1997786850e6110154d4c78faffd?src=pr&el=desc) will **increase** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/26106/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26106?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26106      +/-   ##
==========================================
+ Coverage   91.96%   91.97%   +0.01%     
==========================================
  Files         175      175              
  Lines       52405    52377      -28     
==========================================
- Hits        48192    48176      -16     
+ Misses       4213     4201      -12
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.53% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.71% <ø> (-0.15%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26106?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.61% <ø> (ø)` | :arrow_up: |
| [pandas/util/\_doctools.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX2RvY3Rvb2xzLnB5) | `0% <0%> (-12%)` | :arrow_down: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-8.56%)` | :arrow_down: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `92.15% <0%> (-0.3%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.9% <0%> (-0.12%)` | :arrow_down: |
| [pandas/io/excel/\_base.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsL19iYXNlLnB5) | `92.82% <0%> (-0.07%)` | :arrow_down: |
| [pandas/core/arrays/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2ludGVydmFsLnB5) | `93.06% <0%> (-0.06%)` | :arrow_down: |
| [pandas/tseries/holiday.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvaG9saWRheS5weQ==) | `93.17% <0%> (-0.04%)` | :arrow_down: |
| [pandas/core/indexes/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9pbnRlcnZhbC5weQ==) | `95.22% <0%> (-0.03%)` | :arrow_down: |
| [pandas/core/arrays/sparse.py](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL3NwYXJzZS5weQ==) | `92.3% <0%> (ø)` | :arrow_up: |
| ... and [13 more](https://codecov.io/gh/pandas-dev/pandas/pull/26106/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26106?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/26106?src=pr&el=footer). Last update [aad7739...d6208f4](https://codecov.io/gh/pandas-dev/pandas/pull/26106?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 lgtm. @WillAyd  Thanks @sandepp123 