Document usage of onDidChangeKeyboardLayout function

[spoenemann]

Tested on Mac OS 10.14.3 and Windows 10 Build 17134 with NodeJS v8.13.0 and v10.11.0

I try to register a callback function with keymap.onDidChangeKeyboardLayout, but that function is never called.

Here's my test repository:
https://github.com/spoenemann/native-keymap-test

Am I missing something?

[alexdima]

I have only tested this module in Electron, and in the main process of Electron. I am not sure if it works in vanilla node, as that is a console application and perhaps does not receive the same events from the OS as a GUI application.

[spoenemann]

I can confirm it works in the Electron main process. This should be documented.

[alexdima]

👍 Added section in README.md