[doc] update comment and doc

Runtime/Component/Axis/Axis.cs

@@ -300,7 +300,7 @@ namespace XCharts.Runtime
         /// <summary>
         /// axis Line.
         /// |坐标轴轴线。
-        /// /// </summary>
+        /// </summary>
         public AxisLine axisLine
         {
             get { return m_AxisLine; }

Runtime/Component/Axis/AxisSplitArea.cs

@@ -26,7 +26,7 @@ namespace XCharts.Runtime
         /// <summary>
         /// Color of split area. SplitArea color could also be set in color array,
         /// which the split lines would take as their colors in turns.
-        /// |Dark and light colors in turns are used by default.
+        /// Dark and light colors in turns are used by default.
         /// |分隔区域颜色。分隔区域会按数组中颜色的顺序依次循环设置颜色。默认是一个深浅的间隔色。
         /// </summary>
         public List<Color32> color

Runtime/Component/Axis/AxisSplitLine.cs

@@ -19,8 +19,15 @@ namespace XCharts.Runtime
         /// |刻度线与轴线的距离。
         /// </summary>
         public float distance { get { return m_Distance; } set { m_Distance = value; } }
+        /// <summary>
+        /// auto color.
+        /// |自动设置颜色。
+        /// </summary>
         public bool autoColor { get { return m_AutoColor; } set { m_AutoColor = value; } }
-
+        /// <summary>
+        /// Interval of Axis splitLine.
+        /// |坐标轴分隔线的显示间隔。
+        /// </summary>
         public int interval
         {
             get { return m_Interval; }

Runtime/Component/Axis/SingleAxis/SingleAxis.cs

@@ -64,11 +64,19 @@ namespace XCharts.Runtime
             get { return m_Bottom; }
             set { if (PropertyUtil.SetStruct(ref m_Bottom, value)) SetAllDirty(); }
         }
+        /// <summary>
+        /// width of axis.
+        /// |坐标轴宽。
+        /// </summary>
         public float width
         {
             get { return m_Width; }
             set { if (PropertyUtil.SetStruct(ref m_Width, value)) SetAllDirty(); }
         }
+        /// <summary>
+        /// height of axis.
+        /// |坐标轴高。
+        /// </summary>
         public float height
         {
             get { return m_Height; }