[feat] engines: added NixOS Wiki

Added unofficial wiki commented out,
as it was not working at the time of writing.
It may, however, be useful in the future

searx/settings.yml

@@ -434,6 +434,23 @@ engines:
     engine: archlinux
     shortcut: al
 
+  - name: nixos wiki
+    engine: mediawiki
+    shortcut: nixw
+    base_url: https://wiki.nixos.org/
+    search_type: text
+    disabled: true
+    categories: [it, software wikis]
+
+  # Responded with 404 when implementing
+  # - name: nixos wiki unofficial
+  #   engine: mediawiki
+  #   shortcut: nixwu
+  #   base_url: https://nixos.wiki/
+  #   search_type: text
+  #   disabled: true
+  #   categories: [it, software wikis]
+
   - name: artic
     engine: artic
     shortcut: arc