Add explanation and separator customization for breadcrumb component

Enhance the Breadcrumb component by adding support for a generator function to dynamically create separators, and include usage examples and explanatory text in the demo.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 6cc5c7da-6689-4391-8349-0b45bd1c8827
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 32682b43-93c5-4c30-a291-774a507229bc
Replit-Helium-Checkpoint-Created: true

Author: janrozic1

attached_assets/targeted_element_1765523011666.png

@@ -18,6 +18,8 @@ You can also pass a generator function that receives the previous item and index
 </docs>
 
 <template>
+  <p style="margin-bottom: 16px">Using Breadcrumb.Separator component for custom separators:</p>
+
   <a-breadcrumb separator="">
     <a-breadcrumb-item>Location</a-breadcrumb-item>
     <a-breadcrumb-separator>:</a-breadcrumb-separator>