Review fixes: ordered doc-snippet check, one page and doc per ID, fade test clock, listen-address docs, false placeholder gap, Today param

docs/components/060-segmented-control.md

@@ -7,10 +7,12 @@
 ## 最小示例
 
 ```go
-mujica.SegmentedControl(c, &view, []mujica.Segment{
+if mujica.SegmentedControl(c, &view, []mujica.Segment{
 	{Label: "List", Icon: icons.Must("list"), HideLabel: true},
 	{Label: "Grid", Icon: icons.Must("layout-grid"), HideLabel: true},
-}, mujica.SegmentedControlOptions{Label: "View"})
+}, mujica.SegmentedControlOptions{Label: "View"}).Changed() {
+	fmt.Println("view", view)
+}
 ```
 
 签名：`func SegmentedControl(c *ui.Context, selected *int, segments []Segment, opts SegmentedControlOptions) *ui.Element`