DOC: Fix a typo in indexing.rst
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15916?src=pr&el=h1) Report
> Merging [#15916](https://codecov.io/gh/pandas-dev/pandas/pull/15916?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/1fbdc23def1cc91280c508ac5b7806ced579b264?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/15916/graphs/tree.svg?width=650&src=pr&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/15916?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #15916   +/-   ##
=======================================
  Coverage   90.96%   90.96%           
=======================================
  Files         145      145           
  Lines       49534    49534           
=======================================
  Hits        45057    45057           
  Misses       4477     4477
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.72% <ø> (ø)` | :arrow_up: |
| #single | `40.63% <ø> (ø)` | :arrow_up: |


------

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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
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