🍎 Add 'Hide' to App API for OS X only

docs/api/app.md

@@ -244,6 +244,10 @@ This method guarantees that all `beforeunload` and `unload` event handlers are
 correctly executed. It is possible that a window cancels the quitting by
 returning `false` in the `beforeunload` event handler.
 
+### `app.hide()` _OS X_
+
+Hides all application windows without minimising them.
+
 ### `app.exit(exitCode)`
 
 * `exitCode` Integer