Update documentation for rename
- [x] closes #13473
- [ ] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [ ] whatsnew entry

needs an update to the doc string as well
 Updated docstring
 ## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13533?src=pr) is **84.33%**

> Merging [#13533](https://codecov.io/gh/pydata/pandas/pull/13533?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will not change coverage

``` diff
@@             master     #13533   diff @@
==========================================
  Files           138        138          
  Lines         51111      51111          
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
  Hits          43107      43107          
  Misses         8004       8004          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last updated by [3944a36...8402b95](https://codecov.io/gh/pydata/pandas/compare/3944a369265f27268d1b3867a161e97f9c63cd62...8402b954d8e74a61fa34be6e719e2058f7c17661)
 @gliptak A small grammatical comment, otherwise looks good!
 Thanks!
