Add the kotlin blocks to the documents (#1170)

docs/chapter_tree/array_representation_of_tree.md

@@ -112,6 +112,12 @@
     int tree[] = {1, 2, 3, 4, INT_MAX, 6, 7, 8, 9, INT_MAX, INT_MAX, 12, INT_MAX, INT_MAX, 15};
     ```
 
+=== "Kotlin"
+
+    ```kotlin title=""
+
+    ```
+
 === "Zig"
 
     ```zig title=""

docs/chapter_tree/avl_tree.md

@@ -200,6 +200,12 @@ AVL 树既是二叉搜索树，也是平衡二叉树，同时满足这两类二
     }
     ```
 
+=== "Kotlin"
+
+    ```kotlin title=""
+
+    ```
+
 === "Zig"
 
     ```zig title=""

docs/chapter_tree/binary_tree.md

@@ -176,6 +176,12 @@
     }
     ```
 
+=== "Kotlin"
+
+    ```kotlin title=""
+
+    ```
+
 === "Zig"
 
     ```zig title=""
@@ -397,6 +403,12 @@
     n2->right = n5;
     ```
 
+=== "Kotlin"
+
+    ```kotlin title="binary_tree.kt"
+
+    ```
+
 === "Zig"
 
     ```zig title="binary_tree.zig"
@@ -542,6 +554,12 @@
     n1->left = n2;
     ```
 
+=== "Kotlin"
+
+    ```kotlin title="binary_tree.kt"
+
+    ```
+
 === "Zig"
 
     ```zig title="binary_tree.zig"