improve typings for legend action parameters (apache/echarts#21025)

Author: plainheart

en/api/action.md

@@ -178,11 +178,9 @@ dispatchAction({
 
     // The following parameters are supported since v5.6.0
     // the id of target legend component
-    legendId: string,
+    legendId?: string | string[],
     // the index of target legend component
-    legendIndex: number,
-    // the name of target legend component
-    legendName: string
+    legendIndex?: number | number[]
 })
 ```
 
@@ -197,23 +195,27 @@ dispatchAction({
 
     // The following parameters are supported since v5.6.0
     // the id of target legend component
-    legendId: string,
+    legendId?: string | string[],
     // the index of target legend component
-    legendIndex: number,
-    // the name of target legend component
-    legendName: string
+    legendIndex?: number | number[]
 })
 ```
 
 **EVENT:** [legendinverseselect](~events.legendinverseselect)
 
 ### legendScroll(Action)
 Control the scrolling of legend. It works when [legend.type](option.html#legend.type) is `'scroll'`.
+
 ```ts
 dispatchAction({
     type: 'legendScroll',
+    // the index of the legend item to scroll to
     scrollDataIndex: number,
-    legendId: string
+
+    // the id of target legend component
+    legendId?: string | string[],
+    // the index of target legend component
+    legendIndex?: number | number[]
 })
 ```
 

zh/api/action.md

@@ -178,11 +178,9 @@ dispatchAction({
 
     // 下列参数自 v5.6.0 起开始支持
     // 图例组件ID
-    legendId: string,
+    legendId?: string | string[],
     // 图例组件索引
-    legendIndex: number,
-    // 图例组件名称
-    legendName: string
+    legendIndex?: number | number[]
 })
 ```
 
@@ -197,23 +195,27 @@ dispatchAction({
 
     // 下列参数自 v5.6.0 起开始支持
     // 图例组件ID
-    legendId: string,
+    legendId?: string | string[],
     // 图例组件索引
-    legendIndex: number,
-    // 图例组件名称
-    legendName: string
+    legendIndex?: number | number[]
 })
 ```
 
 **EVENT:** [legendinverseselect](~events.legendinverseselect)
 
 ### legendScroll(Action)
 控制图例的滚动。当 [legend.type](option.html#legend.type) 为 `'scroll'` 时有效。
+
 ```ts
 dispatchAction({
     type: 'legendScroll',
+    // 要滚动到的目标图例项索引
     scrollDataIndex: number,
-    legendId: string
+
+    // 图例组件ID
+    legendId?: string | string[],
+    // 图例组件索引
+    legendIndex?: number | number[]
 })
 ```