chore: Update the design of the help center portal (#6775)

app/views/public/api/v1/models/_article.json.jbuilder

@@ -7,6 +7,7 @@ json.status article.status
 json.position article.position
 json.account_id article.account_id
 json.last_updated_at article.updated_at
+json.slug article.slug
 
 if article.portal.present?
   json.portal do