Rename category-ids

.github/CONTRIBUTING.md

@@ -5,7 +5,7 @@ A new entry should update **contents.json** with this format:
 ```js
 {
             "title": "Name of the app",
-            "category": "Category name",
+            "category-ids": ["Category id"],
             "description": "What this app does",
             "source": "Link to source, usually GitHub",
             "screenshots": ["http://something.com/image.png"],

.github/osia_convert.rb

@@ -23,7 +23,7 @@ def apps_for_cat(apps, id)
   end
 
   s = f.select do |a|
-    cat = a['category']
+    cat = a['category-ids']
     cat.class == Array ? cat.include?(id) : (cat == id)
   end
   s.sort_by { |k, v| k['title'].downcase }

.github/osia_validate_categories.rb

@@ -16,7 +16,7 @@ end
 allowed_categories = osia_allowed_categories(c)
 
 apps.each do |a|
-  cat = a['category']
+  cat = a['category-ids']
 
   if cat.nil?
     puts "missing category for #{a}"