Replace occurrences of "Mac OS X" with "macOS"
Apple's main Operating system changed their name from OS X to macOS: https://www.engadget.com/2016/06/13/os-x-is-now-macos/
This Pull Request changing names of it.
Edited by Brad King
Apple's main Operating system changed their name from OS X to macOS: https://www.engadget.com/2016/06/13/os-x-is-now-macos/
This Pull Request changing names of it.