docs: add routing page (#9550)

- Add a new homepage to `book` project for the routing page
- Move all main doc pages to be under `/v2/learn` (and added redirects + fixed links across docs)
- Other: add admin components to resources dropdown + fixes to search on mobile.

Closes DX-955

Preview: https://docs-v2-git-docs-router-page-medusajs.vercel.app/v2

www/apps/ui/src/app/layout.tsx

@@ -4,7 +4,7 @@ import { Providers } from "@/providers"
 
 import { siteConfig } from "@/config/site"
 import "../styles/globals.css"
-import { TightLayout } from "docs-ui"
+import { BareboneLayout, TightLayout } from "docs-ui"
 import { Inter, Roboto_Mono } from "next/font/google"
 import clsx from "clsx"
 
@@ -33,15 +33,16 @@ export default function RootLayout({
   children: React.ReactNode
 }) {
   return (
-    <TightLayout
-      ProvidersComponent={Providers}
-      sidebarProps={{
-        expandItems: true,
-      }}
-      bodyClassName={clsx(inter.variable, robotoMono.variable)}
-      showBanner={false}
-    >
-      {children}
-    </TightLayout>
+    <BareboneLayout htmlClassName={clsx(inter.variable, robotoMono.variable)}>
+      <TightLayout
+        sidebarProps={{
+          expandItems: true,
+        }}
+        showBanner={false}
+        ProvidersComponent={Providers}
+      >
+        {children}
+      </TightLayout>
+    </BareboneLayout>
   )
 }