docs: Add TreeSelect get parent in FAQ (#15834)

* add faq

* adjust url

components/tree-select/index.en-US.md

@@ -74,3 +74,9 @@ Any data whose entries are defined in a hierarchical manner is fit to use this c
 | key | Required property (unless using `treeDataSimpleMode`), should be unique in the tree | string | - |
 | title | Content showed on the treeNodes | string\|ReactNode | '---' |
 | value | Will be treated as `treeNodeFilterProp` by default, should be unique in the tree | string | - |
+
+## FAQ
+
+### How to get parent node?
+
+We don't provide this since performance consideration. You can get by this way: <https://codesandbox.io/s/wk080nn81k>

components/tree-select/index.zh-CN.md

@@ -74,3 +74,9 @@ title: TreeSelect
 | key | 此项必须设置（其值在整个树范围内唯一） | string | - |
 | title | 树节点显示的内容 | string\|ReactNode | '---' |
 | value | 默认根据此属性值进行筛选（其值在整个树范围内唯一） | string | - |
+
+## FAQ
+
+### 如何获得父节点信息？
+
+从性能角度考虑，我们默认不透出父节点信息。你可以这样获得：<https://codesandbox.io/s/wk080nn81k>