增加代码API注释文档，整理代码

Scripts/UI/Internal/AxisTick.cs

@@ -3,6 +3,10 @@ using UnityEngine;
 
 namespace XCharts
 {
+    /// <summary>
+    /// Settings related to axis tick.
+    /// 坐标轴刻度相关设置。
+    /// </summary>
     [System.Serializable]
     public class AxisTick
     {
@@ -11,9 +15,25 @@ namespace XCharts
         [SerializeField] private bool m_Inside;
         [SerializeField] private float m_Length;
 
+        /// <summary>
+        /// Set this to false to prevent the axis tick from showing.
+        /// 是否显示坐标轴刻度。
+        /// </summary>
         public bool show { get { return m_Show; } set { m_Show = value; } }
+        /// <summary>
+        /// Align axis tick with label, which is available only when boundaryGap is set to be true in category axis.
+        /// 类目轴中在 boundaryGap 为 true 的时候有效，可以保证刻度线和标签对齐。
+        /// </summary>
         public bool alignWithLabel { get { return m_AlignWithLabel; } set { m_AlignWithLabel = value; } }
+        /// <summary>
+        /// Set this to true so the axis labels face the inside direction.
+        /// 坐标轴刻度是否朝内，默认朝外。
+        /// </summary>
         public bool inside { get { return m_Inside; } set { m_Inside = value; } }
+        /// <summary>
+        /// The length of the axis tick.
+        /// 坐标轴刻度的长度。
+        /// </summary>
         public float length { get { return m_Length; } set { m_Length = value; } }
 
         public static AxisTick defaultTick