Add Ruby code blocks to the documents (#1200)

* Add Ruby code blocks to documents

* Remove Ruby code from en/docs

docs/chapter_tree/avl_tree.md

@@ -211,6 +211,12 @@ AVL 树既是二叉搜索树，也是平衡二叉树，同时满足这两类二
     }
     ```
 
+=== "Ruby"
+
+    ```ruby title=""
+
+    ```
+
 === "Zig"
 
     ```zig title=""