Fix webdriver.io guide link (#3165)

.github/CONTRIBUTING.md

@@ -25,7 +25,7 @@ Unit tests are using Jest and can be run with:
 npm run test:unit
 ```
 
-For end-to-end tests, we use [Webdriverio](http://webdriver.io). For it to run locally, you need to install a Selenium standalone server. Follow [the Webdriverio guide](http://webdriver.io/guide.html) to do so. You can also install a Selenium standalone server from NPM:
+For end-to-end tests, we use [Webdriverio](http://webdriver.io). For it to run locally, you need to install a Selenium standalone server. Follow [the Webdriverio guide](https://webdriver.io/docs/selenium-standalone-service) to do so. You can also install a Selenium standalone server from NPM:
 
 ```bash
 npm install selenium-standalone -g