fix: issue ant-design#34015 cascader document of option less isleaf param (ant-design#34174)

* fix: issue ant-design#34015 cascader document of option less isleaf param

* fix: add comment

* fix: comment change

Co-authored-by: zengguhao.zgh <[email protected]>

Author: LongHaoo

components/cascader/index.en-US.md

@@ -75,6 +75,10 @@ interface Option {
   label?: React.ReactNode;
   disabled?: boolean;
   children?: Option[];
+  // Determines if this is a leaf node(effective when `loadData` is specified).
+  // `false` will force trade TreeNode as a parent node.
+  // Show expand icon even if the current node has no children.
+  isLeaf?: boolean;
 }
 ```
 

components/cascader/index.zh-CN.md

@@ -77,6 +77,9 @@ interface Option {
   label?: React.ReactNode;
   disabled?: boolean;
   children?: Option[];
+  // 标记是否为叶子节点，设置了 `loadData` 时有效
+  // 设为 `false` 时会强制标记为父节点，即使当前节点没有 children，也会显示展开图标
+  isLeaf?: boolean;
 }
 ```