feat: add Google Group redirect

Author: denny0223

links.json

@@ -43,6 +43,18 @@
     "title": "SITCON學生計算機年會 Telegram",
     "description": "在 Telegram 上與 SITCON 的夥伴們抬槓吧！"
   },
+  {
+    "paths": [
+      "mailing-list",
+      "ml",
+      "google-group",
+      "sitcon-general",
+      "general"
+    ],
+    "url": "https://groups.google.com/g/sitcon-general",
+    "title": "SITCON 學生計算機年會 Google Group",
+    "description": "加入 SITCON General mailing list，接收社群公告並參與討論吧！"
+  },
   {
     "paths": [
       "plurk"