Use XDG categories for the website

[probonopd]

Use XDG categories for the website, instructions: https://kylewbanks.com/blog/creating-category-pages-in-jekyll-without-plugins

Categories are implemented using Jekyll Collections: https://alligator.io/jekyll/collections/

[probonopd]

Largely done. Remaining piece: Figure out how to get the en translation given a XDG category string. This could be used in

https://github.com/AppImage/appimage.github.io/blob/37a04f42f61aab95a2baa4cc36fa903b74e8dc52/_layouts/post.html#L10

and

https://github.com/AppImage/appimage.github.io/tree/master/_categories

Failed attempt:

{% assign xdg = page.name %}
# https://stackoverflow.com/questions/34162726/getting-a-specific-item-from-a-collection-in-jekyll
{% assign title = site.data.categories.en | where:"xdg", xdg  | first %}
{% assign subtitle = site.data.categories.subtitle | where:"xdg", xdg  | first %}
{% assign image = "https://cdn.stocksnap.io/img-thumbs/960w/" | append: site.data.categories.stocksnap | where:"xdg", xdg  | first | append: ".jpg" %}

https://raw.githubusercontent.com/AppImage/appimage.github.io/6399c67feb5d92f7432b0bcc11c8ef1c955b0c7c/_categories/Audio.md