feat(series): add DDR X(US) info

Author: nogic1008

content/series/.seriesList.json

@@ -183,5 +183,10 @@
     "title": "Dance Dance Revolution (US)",
     "backgroundColor": "mediumvioletred",
     "color": "#fff"
+  },
+  "x-us": {
+    "title": "Dance Dance Revolution X (US)",
+    "backgroundColor": "gold",
+    "color": "#000"
   }
 }

content/series/x-us.md

@@ -0,0 +1,35 @@
+---
+slug: "x-us"
+platform: "Play Station 2"
+region: "US"
+launched: "2008-09-16"
+difficulties:
+  0: { name: "BEGINNER", class: "is-beginner" }
+  1: { name: "BASIC", class: "is-basic" }
+  2: { name: "DIFFICULT", class: "is-difficult" }
+  3: { name: "EXPERT", class: "is-expert" }
+  4: { name: "CHALLENGE", class: "is-challenge" }
+---
+
+# DanceDanceRevolution X
+
+|発売日|機種|リージョン|
+|------|----|---------|
+|{{ $doc.launched }}|{{ $doc.platform }}|{{ $doc.region }}|
+
+## 収録曲リスト
+
+|Name|Artist|BPM|SINGLE|DOUBLE|
+|----|------|---|------|------|
+
+## システム概要
+
+(WIP)
+
+## 隠し要素
+
+(WIP)
+
+## 他ソフトとの連動
+
+(WIP)