(ios): Document WKUrlSchemeTask (#1152)

* (ios): add WKURLSchemeTaskHook

* Simple method description

* Update www/docs/en/dev/guide/platforms/ios/plugin.md

Co-authored-by: Tim Brust <github@timbrust.de>

Co-authored-by: Tim Brust <github@timbrust.de>

Author: NiklasMerz

www/docs/en/dev/guide/platforms/ios/plugin.md

@@ -225,6 +225,10 @@ terminate and `handleOpenURL` events. See the
 [CDVPlugin.h][CDVPlugin.h] and [CDVPlugin.m][CDVPlugin.m]
 classes for guidance.
 
+### WKURLSchemeTask Hook
+
+The [WKURLSchemeTask](https://developer.apple.com/documentation/webkit/wkurlschemetask) is an interface Cordova's main WKWebView uses to load files from your app's bundle. You can create your own custom schemes or custom loading code for the webview by implementing the `- (BOOL) overrideSchemeTask: (id <WKURLSchemeTask>)urlSchemeTask` method in a plugin.
+
 ## Threading
 
 Plugin methods ordinarily execute in the same thread as the main