docs(readme): update link to authenticated docs (#9705)

readme.md

@@ -204,7 +204,7 @@ Useful documentation, examples, and recipes to get you started.
 
 - [Dealing with variance](./docs/variability.md)
 - [Using Lighthouse programmatically](./docs/readme.md#using-programmatically)
-- [Testing a site with authentication](./docs/readme.md#testing-on-a-site-with-authentication)
+- [Testing a site with authentication](./docs/authenticated-pages.md)
 - [Developing Plugins](./docs/plugins.md)
 - [Testing on a mobile device](./docs/readme.md#testing-on-a-mobile-device)
 - [Lighthouse Architecture](./docs/architecture.md)