[feature][axis] add showStartLine and showEndLine for AxisSplitLine

Documentation/XChartsConfiguration-EN.md

@@ -357,6 +357,8 @@ Split line of axis in grid area.
 |`interval`|||Interval of Axis splitLine.
 |`distance`|||The distance between the split line and axis line.
 |`autoColor`|||auto color.
+|`showStartLine`|true|v3.3.0|Whether to show the first split line.
+|`showEndLine`|true|v3.3.0|Whether to show the last split line.
 
 ## `AxisTheme`
 

Documentation/XChartsConfiguration-ZH.md

@@ -357,6 +357,8 @@ Inherits or Implemented: [BaseLine](#BaseLine)
 |`interval`|||坐标轴分隔线的显示间隔。
 |`distance`|||刻度线与轴线的距离。
 |`autoColor`|||自动设置颜色。
+|`showStartLine`|true|v3.3.0|是否显示第一条分割线。
+|`showEndLine`|true|v3.3.0|是否显示最后一条分割线。
 
 ## `AxisTheme`