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/book/tailwind.config.js

@@ -32,6 +32,8 @@ module.exports = {
       "search-no-result-dark": "url('/images/search-no-result.svg')",
       "magnifying-glass": "url('/images/magnifying-glass.svg')",
       "magnifying-glass-dark": "url('/images/magnifying-glass-dark.svg')",
+      "bg-stripes": "url('/v2/images/bg-stripes.png')",
+      "bg-stripes-dark": "url('/v2/images/bg-stripes-dark.png')",
     },
   },
 }