Add TOC entry for tidb-cloud-premium.md in download utils

Author: shhdgit

packages/download/utils.js

@@ -27,6 +27,7 @@ const CLOUD_TOC_LIST = [
   "TOC-tidb-cloud.md",
   "TOC-tidb-cloud-starter.md",
   "TOC-tidb-cloud-essential.md",
+  "TOC-tidb-cloud-premium.md",
 ];
 
 const isCloudTOC = (relativePathInZip) => {