[Doc] optimize data structure table (#3854)

src/coupon-list/README.md

@@ -105,9 +105,9 @@ export default {
 | change | Triggered when change chosen coupon | index: index of chosen coupon |
 | exchange | Triggered when exchange coupon | code: exchange code |
 
-### Coupon Data Structure
+### Data Structure of Coupon
 
-| key | Description | Type |
+| Key | Description | Type |
 |------|------|------|
 | id | Id | `string` |
 | name | Name | `string` |

src/coupon-list/README.zh-CN.md

@@ -109,7 +109,7 @@ export default {
 
 ### Coupon 数据结构
 
-| key | 说明 | 类型 |
+| 键名 | 说明 | 类型 |
 |------|------|------|
 | id | 优惠券 id | `string` |
 | name | 优惠券名称 | `string` |