docs: mention config/sidebars run in Node.js runtime (#10608)

packages/create-docusaurus/templates/classic/sidebars.js

@@ -1,3 +1,7 @@
+// @ts-check
+
+// This runs in Node.js - Don't use client-side code here (browser APIs, JSX...)
+
 /**
  * Creating a sidebar enables you to:
  - create an ordered group of docs
@@ -7,11 +11,9 @@
  The sidebars can be generated from the filesystem, or explicitly defined here.
 
  Create as many sidebars as you want.
+
+ @type {import('@docusaurus/plugin-content-docs').SidebarsConfig}
  */
-
-// @ts-check
-
-/** @type {import('@docusaurus/plugin-content-docs').SidebarsConfig} */
 const sidebars = {
   // By default, Docusaurus generates a sidebar from the docs folder structure
   tutorialSidebar: [{type: 'autogenerated', dirName: '.'}],