docs(descriptions): add labelStyle usage instruction (#4950)

* docs(descriptions): add labelStyle usage instruction

* chore: update docs

---------

Co-authored-by: wū yāng <uyarnchen@gmail.com>

src/descriptions/descriptions.en-US.md

@@ -12,13 +12,12 @@ column | Number | 2 | count of DescriptionItem in one row | N
 contentStyle | Object | - | style of description content。Typescript：`Styles`。[see more ts definition](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 itemLayout | String | horizontal | layout direction of description item。options: horizontal/vertical | N
 items | Array | - | list of descriptions items。Typescript：`Array<TdDescriptionItemProps>` | N
-labelStyle | Object | - | style of description item。Typescript：`Styles`。[see more ts definition](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
+labelStyle | Object | - | style of description item, which takes effect when `tableLayout` is `auto`。Typescript：`Styles`。[see more ts definition](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 layout | String | horizontal | layout direction。options: horizontal/vertical | N
 size | String | medium | a descriptions has three size。options: small/medium/large。Typescript：`SizeEnum`。[see more ts definition](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 tableLayout | String | fixed | Sets the algorithm used to layout `table` cells, rows, and columns, exactly the same as the native table-layout css property. `fixed`: uses fixed layout algorithm; `auto`: uses automatic layout algorithm. For more details, see [MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/table-layout)。options: fixed/auto | N
 title | String / Slot / Function | - | title of descriptions。Typescript：`string \| TNode`。[see more ts definition](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 
-
 ### DescriptionItem Props
 
 name | type | default | description | required

src/descriptions/descriptions.md

@@ -12,13 +12,12 @@ column | Number | 2 | 一行 `DescriptionItem` 的数量 | N
 contentStyle | Object | - | 自定义描述项内容的样式。TS 类型：`Styles`。[通用类型定义](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 itemLayout | String | horizontal | 描述项的排列方向。可选项：horizontal/vertical | N
 items | Array | - | 描述项的列表。TS 类型：`Array<TdDescriptionItemProps>` | N
-labelStyle | Object | - | 自定义描述项标签的样式。TS 类型：`Styles`。[通用类型定义](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
+labelStyle | Object | - | 自定义描述项标签的样式，需要配合 `tableLayout` 为 `auto` 才可以生效。TS 类型：`Styles`。[通用类型定义](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 layout | String | horizontal | 排列方向。可选项：horizontal/vertical | N
 size | String | medium | 组件尺寸。可选项：small/medium/large。TS 类型：`SizeEnum`。[通用类型定义](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 tableLayout | String | fixed | 用于设置底层 `table` 单元格、行和列的布局算法，与原生 table-layout css 属性完全一致。`fixed`：采用固定布局算法；`auto`：采用自动布局算法。详情可参考 [MDN](https://developer.mozilla.org/en-US/docs/Web/CSS/table-layout)。可选项：fixed/auto | N
 title | String / Slot / Function | - | 描述列表的标题。TS 类型：`string \| TNode`。[通用类型定义](https://github.com/Tencent/tdesign-vue-next/blob/develop/src/common.ts) | N
 
-
 ### DescriptionItem Props
 
 名称 | 类型 | 默认值 | 描述 | 必传