refactor: update content structure and layout templates

- Updated author format in content files
- Added section field to content files
- Simplified categories format
- Removed no-category.html layout
- Updated list.html and single.html layouts
- Updated index.html layout
- Updated generate-content.js script
- Do not index content with git

content/vpn/2020-05-utiliser-vpn-gratuit/index.md

@@ -6,9 +6,10 @@ slug: "utiliser-vpn-gratuit"
 wordpress_id: 520
 excerpt: "Il est aujourd’hui difficile de se passer d’un VPN surtout lorsqu’on télécharger ou que l’on souhaite garder un…\n"
 featured_image: "https://www.mistergeek.net/wp-content/uploads/2023/03/vpn-gratuit-scaled.jpg"
-author: {"id":1,"name":"Kevin"}
-categories: [{"id":18,"name":"VPN","slug":"vpn"}]
+author: "Kevin"
+categories: ["VPN"]
 tags: []
+section: "vpn"
 ---
 
 </p>