Keystroke counting requires new permissions in Mac OSX

[samueldowd]

This line should be added at line 29 on the readme.md:

5. As of Mac OS 10.14 there is an additional permission that needs to be granted to the shell script in order to count keystrokes. To do so, go to System Preferences > Security & Privacy > Input Monitoring, add ulogme/osx/dist/ulogme_osx and make sure it is checked off. Lock the settings, and restart the script and keystrokes should begin to get recorded.