docs: support multiple sidebars in a project (#11768)

* changed to new sidebar across projects except resources

* finalize multi sidebar support

* clean up

* remove redundant property

* small changes

* fixes

* generate

* fix error

* fix initial open

www/apps/resources/app/storefront-development/page.mdx

@@ -20,4 +20,4 @@ You can build your storefront from scratch, or built it on top of the [Next.js S
 
 ---
 
-<ChildDocs hideItems={["General"]} />
+<ChildDocs hideItems={["General", "Overview"]} />