Update docs markdown file weight to make it clear (#23909)

For Docusaurus, it needs a meta data named `sidebar_position`, so we
copy all `weight` under `menu/sidebar` as top meta key.

docs/content/doc/packages/pub.en-us.md

@@ -2,6 +2,7 @@
 date: "2022-07-31T00:00:00+00:00"
 title: "Pub Packages Repository"
 slug: "usage/packages/pub"
+weight: 90
 draft: false
 toc: false
 menu: