Add missing newline
The line ">>> idx.isin([1, 4]) array([ True, False, False])" is was not rendered properly, because it was missing a newline above it.

https://pandas.pydata.org/docs/reference/api/pandas.Index.isin.html

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @davidwales! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-03-03 02:21:11 UTC Great thanks @davidwales 