docs(ui,docs): added upgrade guides link to UI docs (#5240)

* added medusa ui index page

* remove console

www/apps/docs/content/upgrade-guides/medusa-ui/index.mdx

@@ -0,0 +1,11 @@
+---
+sidebar_custom_props:
+  exclude_from_auto_sidebar: true
+  exclude_from_doc_list: true
+---
+
+import DocCardList from '@theme/DocCardList';
+
+# Medusa UI Upgrade Guides
+
+<DocCardList colSize={6} />