DOC: OSX -> macOS
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

@partev are there any other references in the codebase? @alimcmaster1 I haven't searched the whole codebase for other references. > @alimcmaster1 I haven't searched the whole codebase for other references.

I have doubled checked - these are the only references in the user docs. LGTM thanks @partev 