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/Link/index.tsx

@@ -2,6 +2,7 @@ import React from "react"
 import NextLink from "next/link"
 import type { LinkProps as NextLinkProps } from "next/link"
 import clsx from "clsx"
+import { TriangleRightMini } from "@medusajs/icons"
 
 export type LinkProps = {
   href?: string
@@ -9,9 +10,16 @@ export type LinkProps = {
   className?: string
   target?: string
   rel?: string
+  withIcon?: boolean
 } & Partial<NextLinkProps>
 
-export const Link = ({ href, children, className, ...rest }: LinkProps) => {
+export const Link = ({
+  href,
+  children,
+  className,
+  withIcon = false,
+  ...rest
+}: LinkProps) => {
   if (href?.replace(/#.*$/, "").endsWith("page.mdx")) {
     href = href.replace("/page.mdx", "")
   }
@@ -21,10 +29,14 @@ export const Link = ({ href, children, className, ...rest }: LinkProps) => {
       {...rest}
       className={clsx(
         "text-medusa-fg-interactive hover:text-medusa-fg-interactive-hover",
+        withIcon && "flex gap-0.25 items-center group",
         className
       )}
     >
       {children}
+      {withIcon && (
+        <TriangleRightMini className="group-hover:translate-x-docs_0.125 transition-transform" />
+      )}
     </NextLink>
   )
 }