docs: support detecting broken link cross-projects (#10483)

* docs: support detecting broken link cross-projects

* remove double separators

www/apps/book/next.config.mjs

@@ -9,11 +9,27 @@ import {
   crossProjectLinksPlugin,
 } from "remark-rehype-plugins"
 import { sidebar } from "./sidebar.mjs"
+import path from "path"
 
 const withMDX = mdx({
   extension: /\.mdx?$/,
   options: {
     rehypePlugins: [
+      [
+        brokenLinkCheckerPlugin,
+        {
+          crossProjects: {
+            resources: {
+              projectPath: path.resolve("..", "resources"),
+              hasGeneratedSlugs: true,
+            },
+            ui: {
+              projectPath: path.resolve("..", "ui"),
+              contentPath: "src/content/docs",
+            },
+          },
+        },
+      ],
       [
         crossProjectLinksPlugin,
         {
@@ -37,7 +53,6 @@ const withMDX = mdx({
             process.env.VERCEL_ENV === "production",
         },
       ],
-      [brokenLinkCheckerPlugin],
       [localLinksRehypePlugin],
       [
         rehypeMdxCodeProps,