refactor: Replace 结点 with 节点 (#452)

* Replace 结点 with 节点
Update the footnotes in the figures

* Update mindmap

* Reduce the size of the mindmap.png

codes/zig/include/TreeNode.zig

@@ -9,10 +9,10 @@ pub fn TreeNode(comptime T: type) type {
     return struct {
         const Self = @This();
 
-        val: T = undefined,         // 结点值
-        height: i32 = undefined,    // 结点高度
-        left: ?*Self = null,        // 左子结点指针
-        right: ?*Self = null,       // 右子结点指针
+        val: T = undefined,         // 节点值
+        height: i32 = undefined,    // 节点高度
+        left: ?*Self = null,        // 左子节点指针
+        right: ?*Self = null,       // 右子节点指针
 
         // Initialize a tree node with specific value
         pub fn init(self: *Self, x: i32) void {