DOC: add whatsnew for #11920
#11920 (forgot to add to commit when merging)

## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13953?src=pr) is 85.77% (diff: 100%)

> Merging [#13953](https://codecov.io/gh/pydata/pandas/pull/13953?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will increase coverage by **0.47%**

``` diff
@@             master     #13953   diff @@
==========================================
  Files           139        139           
  Lines         50159      52054   +1895   
  Methods           0          0           
  Messages          0          0           
  Branches          0          0           
==========================================
+ Hits          42786      44649   +1863   
- Misses         7373       7405     +32   
  Partials          0          0           
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [cce7993...24628c7](https://codecov.io/gh/pydata/pandas/compare/cce79936ca1790fe9870e8a5b6bccb3dba41b8ae...24628c75c05cd5c1e2f419b09045d43fb03661d9?src=pr)
