🔧 NAVIGATION FIX: Clarify Reference Section Names

IMPROVEMENT:
✅ Changed Intermediate Guide 'Advanced Reference' → 'Reference'
✅ Eliminates confusion with new Advanced Guide section
✅ Clear navigation hierarchy now:
   - Beginners Guide: 'Quick Reference'
   - Intermediate Guide: 'Reference'
   - Advanced Guide: 'Advanced Reference'

Perfect navigation clarity achieved! 🎯

astro.config.mjs

@@ -189,7 +189,7 @@ export default defineConfig({
 							],
 						},
 						{
-							label: 'Advanced Reference',
+							label: 'Reference',
 							items: [
 								{ label: 'Power-User Guide', link: '/intermediate/reference/' },
 							],