Improve front matter "added" params

Add missing ones and add the ability to show or hide the badge

Fixes a few more 404 errors in the version picker

site/content/docs/5.3/components/placeholders.md

@@ -4,7 +4,8 @@ title: Placeholders
 description: Use loading placeholders for your components or pages to indicate something may still be loading.
 group: components
 toc: true
-added: "5.1"
+added:
+  version: "5.1"
 ---
 
 ## About