themes: add Arc UI

closes #280

Author: BeyondMagic

Diff for: docs/assets/img/themes/29957ui.webp

@@ -859,5 +859,19 @@
     "description": "A simple light theme I made to explore the world of Firefox theming.",
     "image": "assets/img/themes/monochromeNeubrutalism.webp",
     "tags": [ "light", "neubrutalislm", "monochrome", "simple", "Kaskapa" ]
+  },
+  {
+    "title": "minimalistest oneliner",
+	"link": "https://github.com/yari-dog/minimalistest-oneliner-librewolf",
+	"description": "buttons are for nerds.",
+	"image": "assets/img/themes/minimalist-oneliner.png",
+	"tags": [ "simple", "oneliner", "oneline", "compact" ]
+  },
+  {
+	  "title": "Arc UI",
+	  "link": "https://github.com/dxdotdev/arc-ui",
+	  "description": "Make your Firefox like the Arc Browser.",
+	  "image": "assets/img/themes/29957ui.webp",
+	  "tags": [ "dxdotdev", "arc browser", "compact", "modern" ]
   }
 ]

Diff for: docs/themes.json

@@ -866,5 +866,12 @@
 	"description": "buttons are for nerds.",
 	"image": "assets/img/themes/minimalist-oneliner.png",
 	"tags": [ "simple", "oneliner", "oneline", "compact" ]
+  },
+  {
+	  "title": "Arc UI",
+	  "link": "https://github.com/dxdotdev/arc-ui",
+	  "description": "Make your Firefox like the Arc Browser.",
+	  "image": "assets/img/themes/29957ui.webp",
+	  "tags": [ "dxdotdev", "arc browser", "compact", "modern" ]
   }
 ]