Change example to work with latest versions of selenium-webdriver (#28231)

See https://github.com/SeleniumHQ/selenium/issues/9286
The existing snippet works with selenium-webdriver <= 3.6.0, but any more recent version seems to require using 'goog:chromeOptions' and forBrowser('chrome').

docs/tutorial/using-selenium-and-webdriver.md

@@ -86,12 +86,12 @@ const driver = new webdriver.Builder()
   // The "9515" is the port opened by chrome driver.
   .usingServer('http://localhost:9515')
   .withCapabilities({
-    chromeOptions: {
+    'goog:chromeOptions': {
       // Here is the path to your Electron binary.
       binary: '/Path-to-Your-App.app/Contents/MacOS/Electron'
     }
   })
-  .forBrowser('electron')
+  .forBrowser('chrome') // note: use .forBrowser('electron') for selenium-webdriver <= 3.6.0
   .build()
 
 driver.get('http://www.google.com')