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/resources/app/commerce-modules/auth/create-actor-type/page.mdx

@@ -12,7 +12,7 @@ Before creating an actor type, you must have a module with a data model represen
 
 <Note title="Tip">
 
-Learn how to create a module in [this guide](!docs!/basics/modules).
+Learn how to create a module in [this guide](!docs!/learn/basics/modules).
 
 </Note>