DOC: Fix a typo in advanced.rst
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15933?src=pr&el=h1) Report
> Merging [#15933](https://codecov.io/gh/pandas-dev/pandas/pull/15933?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/0cfc08cf4584e8442c84c30d53f1dceafeac5abf?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/15933/graphs/tree.svg?height=150&src=pr&token=eZ4WkYLtcO&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/15933?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #15933   +/-   ##
=======================================
  Coverage   90.97%   90.97%           
=======================================
  Files         145      145           
  Lines       49474    49474           
=======================================
  Hits        45007    45007           
  Misses       4467     4467
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.73% <ø> (ø)` | :arrow_up: |
| #single | `40.68% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15933?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/15933?src=pr&el=footer). Last update [0cfc08c...46ba4f7](https://codecov.io/gh/pandas-dev/pandas/pull/15933?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). thanks!