Update tailwind.config.js

Author: mianumairkhalid

packages/guider/tailwind.config.js

@@ -1,5 +1,6 @@
 /** @type {import('tailwindcss').Config} */
 module.exports = {
+  darkMode: 'class',
   prefix: 'gd-',
   content: ['./src/**/*.tsx', './src/**/*.ts'],
   theme: {