docs: change navbar items + breadcrumb improvements (#9209)

- Add a new commerce module navbar item
- Rename Learning Resources to Development Resources (in navbar and across documentation content)
- Improve breadcrumbs to show categories / subcategories

Preview: https://resources-docs-git-docs-navbar-changes-medusajs.vercel.app/v2/resources

www/apps/book/providers/main-nav.tsx

@@ -51,6 +51,9 @@ export const MainNavProvider = ({ children }: MainNavProviderProps) => {
       navItems={navigationDropdownItems}
       reportIssueLink={reportLink}
       editDate={editDate}
+      breadcrumbOptions={{
+        showCategories: false,
+      }}
     >
       {children}
     </UiMainNavProvider>