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/packages/docs-ui/src/components/EditButton/index.tsx

@@ -13,7 +13,8 @@ export const EditButton = ({ filePath }: EditButtonProps) => {
       href={`https://github.com/medusajs/medusa/edit/develop${filePath}`}
       className={clsx(
         "flex w-fit gap-docs_0.25 my-docs_2 items-center",
-        "text-medusa-fg-muted hover:text-medusa-fg-subtle"
+        "text-medusa-fg-muted hover:text-medusa-fg-subtle",
+        "text-compact-small-plus"
       )}
     >
       <span>Edit this page</span>