Fix typo (#92)

Author: risen228

apps/website/docs/web-api/page_visibility.md

@@ -14,7 +14,7 @@ Uses [Page Visibility API](https://developer.mozilla.org/en-US/docs/Web/API/Page
 
 ## Usage
 
-All you need to do is to create an integration by calling `trackWindowFocus` with an integration options:
+All you need to do is to create an integration by calling `trackPageVisibility` with an integration options:
 
 - `setup`: after this [_Event_](https://effector.dev/en/api/effector/event/) all listeners will be installed, and the integration will be ready to use; it is required because it is better to use [explicit initialization _Event_ in the application](/magazine/explicit_start).
 - `teardown?`: after this [_Event_](https://effector.dev/en/api/effector/event/) all listeners will be removed, and the integration will be ready to be destroyed.