Documentation error: SDK 14.2 refers to APP_TIMER_INIT macro

[butch]

In the API reference for app_timer: "Use the USE_SCHEDULER parameter of the APP_TIMER_INIT() macro to select " but higher in the document at Libraries>AppTimer>Migration Guide it says "APP_TIMER_INIT macro has been removed."

[Hung Bui]

Thanks butch.

We will update the documentation to refer to the use of sdk_config.h instead.