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/jeu-video/2019-08-proteger-donnees-jouer/index.md

@@ -6,9 +6,10 @@ slug: "proteger-donnees-jouer"
 wordpress_id: 473
 excerpt: "Les Français et les jeux, ça matche de toutes les manières possibles. Selon une étude menée par BVA…\n"
 featured_image: ""
-author: {"id":2,"name":"Expert"}
-categories: [{"id":5,"name":"Jeu vidéo","slug":"jeu-video"}]
+author: "Expert"
+categories: ["Jeu vidéo"]
 tags: []
+section: "jeu-video"
 ---
 
 <p><!--kg-card-begin: html--></p>