Update the CSS path in the Integrating with Rails (#561)

docs/tutorials/integrating-with-rails.md

@@ -23,9 +23,12 @@ yarn add @shoelace-style/shoelace copy-webpack-plugin
 The next step is to import Shoelace's default theme (stylesheet) in `app/javascript/stylesheets/application.scss`.
 
 ```css
-@import '~@shoelace-style/shoelace/dist/themes/base';
+@import '~@shoelace-style/shoelace/dist/themes/light';
+@import '~@shoelace-style/shoelace/dist/themes/dark'; // Optional dark theme
 ```
 
+Fore more details about themes, please refer to [Theme Basics](/getting-started/themes?id=theme-basics).
+
 ### Importing Required Scripts
 
 After importing the theme, you'll need to import the JavaScript files for Shoelace. Add the following code to `app/javascript/packs/application.js`.