docs: use optional chaining for app.dock (#46119)

docs: use optional chaining for app.dock

docs/api/dock.md

@@ -9,7 +9,7 @@ The following example shows how to bounce your icon on the dock.
 
 ```js
 const { app } = require('electron')
-app.dock.bounce()
+app.dock?.bounce()
 ```
 
 ### Instance Methods