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/informatique/2018-06-spotify-premium-gratuit-ios-iphone/index.md

@@ -6,9 +6,10 @@ slug: "spotify-premium-gratuit-ios-iphone"
 wordpress_id: 299
 excerpt: "Spotify est un service de Streaming de musique incontournable aujourd’hui. En tant que grand consommateur de musique, j’adore…\n"
 featured_image: "https://www.mistergeek.net/wp-content/uploads/2020/12/20150616163611-spotify.jpg"
-author: {"id":1,"name":"Kevin"}
-categories: [{"id":14,"name":"Informatique","slug":"informatique"}]
+author: "Kevin"
+categories: ["Informatique"]
 tags: []
+section: "informatique"
 ---
 
 </p>