Add na_filter documentation to read_excel
- [x] closes #25453
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry (Not needed)

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=h1) Report
> Merging [#26353](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/bb0376c209d97e49b9c94038926ee62ddc0ee84d?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/26353/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26353      +/-   ##
==========================================
- Coverage   92.04%   92.03%   -0.01%     
==========================================
  Files         175      175              
  Lines       52292    52292              
==========================================
- Hits        48133    48128       -5     
- Misses       4159     4164       +5
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.59% <ø> (ø)` | :arrow_up: |
| #single | `40.71% <ø> (-0.17%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/excel/\_base.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsL19iYXNlLnB5) | `92.13% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.01% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.6% <0%> (-0.11%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26353?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/26353?src=pr&el=footer). Last update [bb0376c...3921346](https://codecov.io/gh/pandas-dev/pandas/pull/26353?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/26353?src=pr&el=h1) Report
> Merging [#26353](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b48d1ff87237cb68792590f4377e3be5c73d5ea7?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/26353/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26353      +/-   ##
==========================================
- Coverage   91.68%   91.67%   -0.01%     
==========================================
  Files         174      174              
  Lines       50700    50700              
==========================================
- Hits        46486    46481       -5     
- Misses       4214     4219       +5
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.18% <ø> (ø)` | :arrow_up: |
| #single | `41.17% <ø> (-0.17%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/excel/\_base.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsL19iYXNlLnB5) | `92.13% <ø> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.01% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26353/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.6% <0%> (-0.11%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26353?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/26353?src=pr&el=footer). Last update [b48d1ff...5ac1ae2](https://codecov.io/gh/pandas-dev/pandas/pull/26353?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 CI test failure seems unrelated:
```
Exception: Cython-generated file 'pandas\_libs/algos.c' not found.
                    Cython is required to compile pandas from a development branch.
                    Please install Cython or download a release package of pandas.
``` closing as stale, ping if you'd like to continue.