Clarification of docstring for value_counts
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=h1) Report
> Merging [#25055](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/da5f5eb6c11140a2bb9f84049d30ba7d89bdbfd0?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25055/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25055   +/-   ##
=======================================
  Coverage   92.37%   92.37%           
=======================================
  Files         166      166           
  Lines       52403    52403           
=======================================
  Hits        48405    48405           
  Misses       3998     3998
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.79% <100%> (ø)` | :arrow_up: |
| #single | `42.87% <36%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `97.75% <ø> (ø)` | :arrow_up: |
| [pandas/io/parsers.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhcnNlcnMucHk=) | `95.34% <ø> (ø)` | :arrow_up: |
| [pandas/core/indexes/multi.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9tdWx0aS5weQ==) | `95.59% <100%> (ø)` | :arrow_up: |
| [pandas/core/tools/timedeltas.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvdGltZWRlbHRhcy5weQ==) | `98% <100%> (ø)` | :arrow_up: |
| [pandas/core/resample.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzYW1wbGUucHk=) | `97.24% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `83.58% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/numpy\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL251bXB5Xy5weQ==) | `93.51% <100%> (ø)` | :arrow_up: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.82% <100%> (ø)` | :arrow_up: |
| [pandas/core/internals/concat.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzL2NvbmNhdC5weQ==) | `96.45% <100%> (ø)` | :arrow_up: |
| [pandas/core/indexes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9iYXNlLnB5) | `96.32% <100%> (ø)` | :arrow_up: |
| ... and [12 more](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25055?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/25055?src=pr&el=footer). Last update [da5f5eb...9be2f49](https://codecov.io/gh/pandas-dev/pandas/pull/25055?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/25055?src=pr&el=h1) Report
> Merging [#25055](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/da5f5eb6c11140a2bb9f84049d30ba7d89bdbfd0?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25055/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25055   +/-   ##
=======================================
  Coverage   92.37%   92.37%           
=======================================
  Files         166      166           
  Lines       52403    52403           
=======================================
  Hits        48405    48405           
  Misses       3998     3998
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.79% <100%> (ø)` | :arrow_up: |
| #single | `42.87% <36%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `97.75% <ø> (ø)` | :arrow_up: |
| [pandas/io/parsers.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhcnNlcnMucHk=) | `95.34% <ø> (ø)` | :arrow_up: |
| [pandas/core/indexes/multi.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9tdWx0aS5weQ==) | `95.59% <100%> (ø)` | :arrow_up: |
| [pandas/core/tools/timedeltas.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvdGltZWRlbHRhcy5weQ==) | `98% <100%> (ø)` | :arrow_up: |
| [pandas/core/resample.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzYW1wbGUucHk=) | `97.24% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `83.58% <100%> (ø)` | :arrow_up: |
| [pandas/core/arrays/numpy\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL251bXB5Xy5weQ==) | `93.51% <100%> (ø)` | :arrow_up: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.82% <100%> (ø)` | :arrow_up: |
| [pandas/core/internals/concat.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzL2NvbmNhdC5weQ==) | `96.45% <100%> (ø)` | :arrow_up: |
| [pandas/core/indexes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9iYXNlLnB5) | `96.32% <100%> (ø)` | :arrow_up: |
| ... and [12 more](https://codecov.io/gh/pandas-dev/pandas/pull/25055/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25055?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/25055?src=pr&el=footer). Last update [da5f5eb...9be2f49](https://codecov.io/gh/pandas-dev/pandas/pull/25055?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Looks like there are some unrelated commits here. Did you branch start off master or 0.24.x? (we want master)