docs: update theme guide

src/content/posts/guides/Theme Guide-zh-tw.md

@@ -114,6 +114,19 @@ comment: {
     // 圖片上傳
     imageUploader: false // true, false
   }
+  // giscus
+  // https://giscus.app/
+  giscus: {
+    repo: 'radishzzz/comment-giscus'
+    repoID: 'R_kgDOOy1K0w'
+    category: 'Announcements'
+    categoryID: 'DIC_kwDOOy1K084CqwuZ'
+    mapping: 'pathname'
+    strict: '0'
+    reactionsEnabled: '1'
+    emitMetadata: '0'
+    inputPosition: 'bottom'
+  }
 }
 ```